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WORKS OF 
Professor A. M. GREENE, Jr. 

PUBLISHED BY 

JOHN WILEY & SONS 



Elements of Heating and Ventilation. 

A Text-book for Technical Students and a 
Reference Book for Engineers. 8vo, vi+324 
pages, 223 figures. Cloth, $2.50 net. 

Pumping Machinery. 

A Treatise on the History, Design, Construction, 
and Operation of Various Forms of Pumps. 
8vo, vi +703 pages, 504 figures. Cloth, $4.00 net. 

Refrigeration and Ice Making. In Preparation. 



By SPANGLER, GREENE, AND MARSHALL: 

Elements of Steam Engineering. 

Third Edition, Revised. 8vo, v+296 pages, 
284 figures. Cloth, $3.00. 



THE ELEMENTS 

OF 

HEATING AND VENTILATION 

A TEXT-BOOK 

FOR 

STUDENTS, ENGINEERS AND ARCHITECTS 



BY i^eC- 

ARTHUR M. GREENE, Jr. 

Professor of Mechanical Engineering, Russell Sage Foundaiiofi, Rensselaer Polytechnic 
Institute; Sotnetitne Junior Dean, School of Engineering, University of Missouri 



FIRST EDITION 

FIRST THOUSAND 



NEW YORK 

JOHN WILEY & SONS 

London: CHAPMAN & HALL, Limited 

1913 






Copyright, 1912, 

BY 

ARTHUR M. GREENE. Jr. 



V 






THE SCIENTIFIC PRESS 

ROBERT DRUMMOND AND COMPANY 

BROOKLYN N. Y. 






PREFACE 



The aim of the author in preparing this book has been to 
bring together in logical order and in a small volume the 
necessary data from which to design the heating and venti- 
lating systems of buildings. In doing this he has been guided 
by his own experience in the layout of such systems and by the 
previous works of many authors which he has used. He has 
consulted these works freely, as well as the valuable experi- 
mental data prepared by a number of the companies building 
apparatus for heating and ventilation. Where such work has 
been used credit has been given to the author or the company. 
These data, which in general are scattered among various books 
and pamphlets and must be used by the engineer in his work, 
have been brought together and placed in a logical position in 
a single book. The data are founded on careful experiment 
and may be used with confidence. In selecting these data, 
which are given in the forms of tables and curves, the endeavor 
has been made to include all that are necessary to solve any 
problem which may arise in connection with the warming of 
buildings or the supply and delivery of air. Many of the 
curves and tables are originally given, and in all cases these 
have been recomputed or redrawn for this book. Several 
methods given for the solution of problems are new. 

The book is intended for the use of upper-class men in 
technical schools, for engineers, architects, and superintendents 
of buildings. All phases of the work are illustrated by actual 
problems for which the slide rule has been used. The use of 
the slide rule is recommended and advised for these problems. 
Certain architectural information has been added to aid those 

iii 



IV PEEFACE 

who have not had experience with constructions of various 
forms. 

The plan of the work has been for a continuous course of 
study without any omissions. Each chapter forms a unit in 
the subject of heating and ventilation. The tables and curves 
from commercial apparatus are given to aid in the layout of 
work, so that the engineer may have in one volume the neces- 
sary information for a possible solution. There are many 
different forms of apparatus which have not been mentioned in 
tabular form and these the engineer will probably have in his 
catalogue library. It is impossible to include all in a small 
volume. Those given have been selected because they repre- 
sent common forms in use. 

The author desires to thank his wife, Mary E. Lewis Greene, 
for the care she has taken in the preparation of copy and the 
reading of proof. He desires to thank those authors and manu- 
facturers from whose works he. has gained much as a student, 
or whom he has quoted in this book. 

A. M. G., Jr. 
SuNNYSLOPE, Troy, N. Y., November 26, 191 2. 



TABLE OF CONTENTS 



CHAPTER I 

PAGE 

Methods of Heating and \^extilatixg Buildixgs i 



CPIAPTER II 

AilOUNT AND CONDITION OF AlR FOR VENTILATION 20 

CHAPTER III 
Loss AND Gain of Heat 45 

CHAPTER IV 
Radl\tors, Val\'es and Heat Transmission from Radiators 73 

CHAPTER V 
Methods of Calculating Heat Required for Rooms 118 

CHAPTER VI 
DiEiECT Steam Heating 127 

CHAPTER VII 
Hot-water Heating 153 

CHAPTER VIII 
Indirect Heating 171 

V 



vi TABLE OF CONTENTS 



CHAPTER IX 

PAGE 

Furnace Heating 237 



CHAPTER X 
Furnaces and Boilers 255 

CHAPTER XI 
District Heating 279 

CHAPTER XII 
Temperature Control and Drying by Air 300 



THE ELEMENTS OF HEATING AND 
VENTILATION 



CHAPTER I 
METHODS OF HEATING AND VENTILATING BUILDINGS 

There are several methods of heating buildings in use 
to-day. For small buildings the hot-air fximace is quite com- 
mon. In this, as shown in Fig. i, the heat from the burning of 
coal is used to heat air on the opposite side of the fire pot A or 
radiator B through which the hot gases pass on their way to the 
chimney. The heated air from the dome or top of the heater is 
carried through the leader pipes C to boots D at the bottom of 
the risers or heat stacks E. It rises through the stacks to the 
various register faces F, where it enters the rooms to be heated. 
The air is forced to rise through the ducts by a difference in 
pressure due to the difference in the weight of the hot air inside 
and the cold air outside. The cold air enters at the bottom of 
the heater casing at G, being taken from the outside at H or the 
inside at /. 

In some house work the foul air is removed by vent stacks 
K leading to the attic or to a chimney, while in most installa- 
tions this removal is cared for by leakage of air from the win- 
dows or doors. 

This method of heating is also a method of ventilation if 
the cold air or a part of it is taken from the outside. 

Another common and excellent method of heating is that 
in which radiators, suppHed with hot water or steam, are placed 
in the various rooms or spaces to be heated. As shown in Fig. 2 



2 ELEMENTS OF HEATING AND VENTILATION 

the steam is made or the water is heated in the boiler or heater 
A from which it is taken through the distributing main or flow 




Fig. I . — Hot-air Furnace Heating. 



main B to the various risers C and thence to the radiators D by 
the connections E. The return water or condensed steam known 



HEATING AND VENTILATING BUILDINGS 3 

as the return is carried through branches F, return risers G and 
return main H to the boiler or heater A. The radiators are 




Fig. 2.— Direct Heating by Steam or Hot Water. 



usually placed in front of windows where the up current of 
heated air will form a blanket warming the cold air which may 



* ELEMENTS OF HEATING AND VENTILATION 

enter around the window and keep the same from producing 
cold currents or drafts. Each radiator is controlled by valves 




Fig. 3. — Indirect System of Heating with Individual Stacks. 

on inlet and outlet side. This is known as the direct radiation 
system. 



HEATING AND VENTILATING BUILDINGS 5 

The indirect system of heating is that in which the radiators 
are used to heat air which is introduced into various rooms 




Fig. 4. — Plenum System of Indirect Heating with Single Coil. 



by riser stacks as in the hot-air furnace method. Fig. 3 shows 
this method as appUed to a residence where natural circula- 



ELEMENTS OF HEATING AND VENTILATION 



tion is depended on, while Fig. 4 shows one where a fan blower 
is used. This indirect system is a combined method of heating 




Fig. 5. — Vacuum System of Ventilation with Indirect Heating System. 

and ventilation. It is used where definite ventilation is needed 
or where it is deemed advisable to have no radiators in the 



HEATING AXD VENTILATING BUILDINGS 7 

room. The application of the method of steam heating of Fig. 
3 is often found in buildings of such a size that hot-air furnace 




Fig. 6. — Direct Indirect System. 



systems would not be possible and yet' it is desired to bring the 
heat in by air with natural ventilation. The installation of an 



8 



ELEMENTS OF HEATING AND VENTILATION 



indirect heating coil at the bottom of each stack or group of 
stacks makes this possible and the positive steam circulation 
furnishes the heat to each radiator. The indirect system of 
heating employing a fan blower is found in places where it is 
advisable to centralize most if not all of the heating surface 
in one set of coils and to make the flow of air positive to all 
parts of the building ; a fan blower is used to produce a pressure 
difference. The fan may be employed to drive the air into the 
rooms as shown in Fig. 4, in which case the system is known as 
the plenum system, while in some cases the air is drawn through 
the heating coils and into the room by the suction of a fan which 
discharges the air from the room into the atmosphere. The air 




Fig. 7. — Lamp Radiators of G. E. Co. 



in the room is under reduced pressure and for this reason the 
system is known as the vacuum system of ventilation, Fig. 5. 

At times the ventilation of a room is accomplished by con- 
necting the room to the outer atmosphere by a series of open- 
ings, each leading to a radiator. The radiator is so constructed 
that a series of flues is formed and as the heated air rises 
through these flues cold air enters from the outside. These 
radiators are known as direct-indirect radiators and as usually 
constructed. Fig. 6, they are provided with chambers at the 
base which can be used to cut off the external air when neces- 
sary and permit circulation from the inside. 

The electric method of heating has flexibility, rapidity, and 
convenience in its favor, but its great expense confines its use to 



HEATING AND VENTILATING BUILDINGS 9 

special places and for specific aims. Fig. 7 illustrates a 
luminous form of electric radiator for use in removing the chill 
from bathrooms or dressing rooms where heat is needed on 
short notice and for a short time only. The one on the left is 
known as a three-glower luminous radiator and that on the 
right, a four-glower. Fig. 8 represents coil-resistance radiators 
or air heaters used on steamships, buildings or electric cars, when 





Wall Type Tubular Electric 
Air Heater. 



Stateroom Type Tubular 
Electric x-Vir Heater. 



Fig. 



-Resistance Air Heaters of the G. E. Co. 



the expense of operation and danger from individual hot water 
or hot-air heaters makes this form of heater practicable. 

The glower luminous radiators are made of various capaci- 
ties. Some of them are made small enough to be put on a lamp 
circuit. These are of 500 watts capacity and consist of two glow- 
ers. With four glowers there are two sizes built, one of 1000 
watts and one of 2000 watts. The radiators are built for two 
sets of voltages, 95-125 and 200-225. The tubular air heaters 
shown in Fig. 8 are of the wall type and the stateroom type. 
They are made to dissipate 300 and 500 watts per tube. With 



10 



ELEMENTS OF HEATING AND VENTILATION 



the first consumption there is no danger of reaching a scorching 
temperature. In the case of the stateroom heater the tubes are 
separately controlled and a junction box is shown to connect 




Fig. 9. — Floor and Ceiling Vent. 

to the conduit system. The heating element in these air heaters 
is of special form originally intended for rheostat work; in it the 
wire of special composition is wound on a soft asbestos tube. 



HEATING AND VENTILATING BUILDINGS 



11 



then fixed mechanically and the tube solidified by coating it 
with a fireproof cementing compound. 

The manner of ventilating rooms with the various systems 
of heating described above has been examined, but there yet 
remain several systems for which the accompanying method of 
ventilation has not been described. 

In many installations little or no provision is made for ven- 
tilation, the freshening of the air being produced by leakage 
around windows and doors. Such a method is not reliable and 
except for house or office installation in which there will be few 
occupants in large rooms it should not be employed. 



II II II 11 II II II H II ini inrn 




Fig. io.— Method of Ventilation. 

In some cases the fresh air is supposed to enter from the 
windows or doors while the foul air is taken out through ven- 
tilating ducts leading to the roof or attic. In this case, Fig. 9, 
there are usually two registers leading to the ventilating ducts' 
one at the floor and the other at the ceiling. The air is ordi- 
narily taken from the floor of the room, as this will cause a 
better circulation. The upper register may be used when 
necessary to clear the room rapidly. 

When fresh air is brought into the room from a hot-air 
furnace, fan and heater or from the heating box, this air should 
be delivered near the top of the room on its cold side as shown 
in Fig. 10. In this way the air is thoroughly mixed and there 



12 ELEMENTS OF HEATING AND VENTILATION 

is no chance for the air to short-circuit across the room. If air 
entered at A and was taken out at either B or C there would 
be a chance for ventilating air or in some cases for the heating 
air to be carried out before it had a chance to either heat or 
ventilate it and certain portions of the room would remain 
unprovided for. The supply on the cold wall makes it possible 
for down currents of cold air to pass out at the vent openings 
before mixing with the warmer currents. 

I h When vents alone are placed in a room with direct heaters 
these should be placed on the exposed wall. 

Although this method of bringing the heated air in through 
ducts on the exposed wall has certain advantages, the method 
of ducts in inner partitions is often employed because this 
location can be better arranged in the construction of the build- 
ing and the heat loss from these can be used to warm the build- 
ing, thus the heat will not escape directly to the atmosphere as 
may occur from the outer walls. 

With direct radiation in steam, hot water or electric heating, 
air when introduced is for ventilation only and in such cases the 
air is heated to the temperature desired for the room and not 
above this temperature, as is the case when the air has to sup- 
ply the heat to care for losses through the walls. The air in 
all of these cases should be introduced as described. 

When the air is used for ventilation only it is brought to the 
rooms by ducts at 70° or at the temperature of the room, the 
air being introduced as shown in Fig. 4. In this case, however, 
it is customary to deliver the air into a main and to take 
branches to the various rooms. When, however, the rooms are 
heated as well as ventilated by the air it is then necessary to 
bring in the air at such a temperature that in giving up the heat 
to care for the heat losses it is cooled to the desired room tem- 
perature. Since the amount of heat for the heat losses varies 
in different rooms with an independent variation in the amount 
of ventilation it is necessary to bring air at different tempera- 
tures to the various rooms. This is accomplished by having all 
of the air tempered to about 70° F. and then to take a portion 
of this to a reheater and increase its temperature. 



HEATING AND VENTILATING BUILDINGS 



13 



If now the tempered air and heated ah: are mixed in proper 
amounts any temperature from that of the tempered air to that 
of hot air can be obtained. If the hot air is not mixed with 
the tempered air, the highest temperature is reached while 
tempered air alone will give the lowest temperature. This is 
accompHshed by separating the air into two portions at the 
reheater. If now the tempered air and the heated air are carried 
in pipes, flues or ducts throughout the building, a two-duct or 




Fig. II. — Hand Control of ISIixing Damper. 

double-duct system is the result. In this case two branches are 
carried to each riser duct. The damper at the bottom of this 
riser is hinged at the partition between the two ducts. By rais- 
ing this damper by hand, Fig. ii, or by the thermostatic motor, 
Fig. 12, the air from the top duct is throttled while by lower- 
ing, the lower duct is cut off partially. In this way the tem- 
perature of the room into which the air discharges may be 
regulated. 

At times this mixing is done just beyond the heater as in Fig. 



14 



ELEMENTS OF HEATING AND VENTILATION 



13, and in this case separate lines of single pipes are run from 
this point to the riser for each line. This gives what is known 
as the single-duct system. 



'//.'///mm 



'/v 



I 



Fig. 12. — Motor Control of Mixing Damper. 




Fig. 13. — Single Duct System, 

The use of the ozonator for the purpose of purifying the air 
must be mentioned at this point as well as the claims made by 
certain physiologists that the mere circulation of air will main- 
tain its power of supporting respiration until the carbon dioxide 



HEATING AND VENTILATING BUILDINGS 



15 



content is much higher than the amount usually allowed. As 
will be mentioned in the next chapter many claim that CO2 
is but an indicator of the presence of other impurities. If this 
be so then the circulation of air may cause some of these impuri- 
ties to oxidize and in the case of the use of ozone, the breaking 
down of O3 into O2 and O give an active nascent atom which 
probably oxidizes the impure emanations from the breath and 
purifies the air. Experiments with ozonators have shown this 
to be the case. 

Fig. 14 gives a view of the ozonator built by the General 
Electric Co. This, for alternating currents, consists of an 
electric motor and fan mounted on top of the case which con- 
tains a step-up transformer and six or more ozone generators. 
If direct current is supplied the motor is replaced by a rotary 
converter which not only drives the fan blower but converts 
the direct current into alternating current, so that this may be 
used in the transformer to get a sufficiently high voltage to 
produce a violet discharge but not so high that the discharge 
will be intense enough to produce nitrous oxide. The gen- 
erating units consist of a number of 
glass tubes coated on the outside with 
a metallic coating and having on the 
inside an aluminum electrode com- 
posed of a series of aluminum cups 
mounted on a spindle. The diameter 
of the cups is smaller than that of 
the tube so that there is a small 
definite air-gap between the electrode 
and the tube. The exterior coatings 
are connected in multiple with one 
terminal of the high side of the trans- 
former and the electrodes are con- 
nected in multiple with the other. 
The high alternating voltage induces 
charges on the inside of the tube and 

a violet discharge takes place across the gap, the energy of 
which is used in the production of ozone. The blower on top 




Fig. 14.— G. E. Alternating 
Current Ozonator. 



16 ELEMENTS OF HEATING AND VENTILATION 

forces 4000 cu.ft. of air per hour through the generators and 
this charges the air with six milligrams of ozone per cubic 
meter. To do this requires about 70 watts onA.C. supply and 
87 watts on D.C. supply. There are two switches on the ozonator, 
one controls the whole apparatus, the other, a three-point switch, 
controls the voltage of the transformer, regulating the amount 
of ozone. The first point gives four milligrams per cubic 
meter; the second five, and the third six. The blower is always 
in operation when the first switch is turned on. The trans- 
former may be cut out by the second switch at the off 
position. The ozonator requires 19!'^ in height and has a 
base iiy'Xi4''. 

The results obtained by the apparatus are remarkable as 
the following quotations from the General Electric Bulletin 
4912, from which the above description is taken, will illus- 
trate. 

*' Perhaps one of the most universal applications of ozone 
will be in the treatment of air for the destruction and removal 
of noxious odors, organisms and emanations. This subject has 
received some attention in America where the matter of ozone 
application is a new one, and much attention in Europe, par- 
ticularly in France, where ozone has long been recognized as a 
valuable agent of sanitation. 

''Ozone acts on the air as a bactericide as well as a power- 
ful agency of deodorization. For the purpose of studying the 
power of ozone to destroy noxious odors, Scoutettin chose a 
ward of the hospital at Metz, having a magnitude of about iioo 
cubic meters. In this hall he placed two piles of manure about 
10 meters apart. These manure piles were permitted to remain 
48 hours, during which period the room became filled with a 
pernicious odor indicating an advanced stage of putrefaction, 
as shown by the evidence of the ammonia evolved. 

''When this had been accomplished, two vessels of 8 liters 
capacity were opened in the hall, permitting their contents of 
ozonized air to diffuse therein. The ammoniacal odor dimin- 
ished considerably, though it did not disappear completely. 
The manure was then removed and the experiment repeated. 



HEATING AND VENTILATING BUILDINGS 17 

This time the odor disappeared completely and rapidly, the nox- 
ious gases, hydrogen sulphide, carbon bisulphide and ammonia 
having been destroyed. 

''Experiments with cultures of the tubercular bacilli have 
shown that these grow with only one-fourth the rapidity 
of check cultures, when exposed to the action of ozonized 
air. 

''These results show that where ozonized air comes in con- 
tact with the living colonies their development is impeded; 
but that when the bacterial colony grows deep within the cul- 
ture medium, the action of ozone applied to the surface only is 
less marked, if not altogether imperceptible. 

"This is what should be expected according to Ohlmliller, 
who has demonstrated that the bactericidal action of ozone 
is greatly interfered with in the case of colonies growing on 
organic matter; for the ozone oxidizes the organic medium, 
thus destroying itself, before it makes sensible its action on the 
bacteria. Ozone destroys itself in oxidizing organic matter 
and coagulates albuminous matter. 

"It may be deduced from the foregoing that any extra- 
neous organic matter found in air which it is desired to sterilize, 
will diminish the action of ozone by combining with it; and in 
consequence, the air should be first filtered whenever prac- 
ticable. Many failures to produce sterilization in researches 
on ozonizing air have resulted from the presence of a relatively 
large amount of organic matter in the air. 

"Ozone will find an application in the sterilization and deo- 
dorization of the air of hospitals, apartments, studios, schools, 
etc., wherever there is likely to be large crowds. 

"In stables, chicken coops, toilets and factories, where there 
are evolved noxious emanations, ozone will greatly ameliorate 
the conditions. In particular, the shops for assorting rags, 
manufacture of fertilizers and factories which work gelatin, 
glue, hides, hair, fat, bones, horn and other slaughter-house 
by-products, and those which are a source of emanations 
dangerous to the pubHc health, will find in ozone a powerful 
ally. 



18 ELEMENTS OF HEATING AND VENTILATION 

''Wherever pure sterile air is of value in the factory either 
before, during, or after the completion of the product, e.g., 
distilleries, breweries, wine houses, etc., the use of ozone should 
be resorted to. 

"The Art Theater on State Street, Schenectady, a moving- 
picture show, had experienced difficulty with its ventilation. 
The theater consists of a hall about 30 by 100 feet, and the ven- 
tilation is provided by a suction blower capable of aspirating 
about ninety thousand cubic feet per hour. The management 
were very desirous of providing the best ventilation possible, 
as is evidenced by the elaborate and expensive system cited. It 
was found, however, that notwithstanding the magnitude of the 
blower, ' crowd odors ' persisted in the room. The blower was 
as large as could be used, for anything larger would have pro- 
duced obnoxious drafts. 

"As a solution to the trouble, an ozonator was installed above 
the front entrance to the theater, in such a way as to permit the 
ozonized air to diffuse into the current of ventilating air drawn 
toward the aspirator. The instantaneous effect of this was 
remarkable. The theater has been entirely deodorized and 
even during the hottest weather of the past summer the air 
within the theater has been fresh, cool and odorless, excepting 
for the faint and rather pleasant smell of the slight excess of 
ozone. 

"The next case which we may cite provides an even more 
remarkable instance of the efficacy of ozone in deodorizing 
obnoxious air, since this case relates to a factory in which, 
through the nature of the work carried on, emanations are 
evolved, which constitute a vehicle of certain volatilized dilu- 
ents and solvents of the varnishes and adhesives used. In a 
workshop some 75 feet by 200 feet upwards of two hundred 
girls are employed in the preparation of various articles of 
pasted mica. It is easy to realize that the problem of providing 
clean air under such conditions will always be a difficult one, 
and in the present instance a considerable expenditure of money 
and ingenuity was incurred before the correct solution was 
found. 



HEATING AND VENTILATING BUILDINGS 19 

" Finally two ozonators were installed, one near each end of 
the room, and the windows which had to be wide open to 
clear the air were now only slightly open. A number of other 
instances are recorded in this bulletin showing the usefulness 
of this apparatus," 



CHAPTER II 
AMOUNT AND CONDITION OF AIR FOR VENTILATION 

Am is composed principally of nitrogen and oxygen with 
small quantities of carbon dioxide, water vapor and the rare 
element, argon. 

The amounts of the various constituents are given below: 

By Weight. By Volume. 

Nitrogen 75 50% 78.06% 

Oxygen 23.20 2 1 . 00 

Argon 1.3 .94 

Approximately this is 

Nitrogen 77 . 79 . 

Oxygen 23 . 21 . 

Helium, metargon, neon, krypton, and xenon have been dis- 
covered in air in small but constant amounts. 

Free air is found to contain from 3 to 4 parts of CO2 in 
10,000 parts by volume. 

The amount of water vapor contained in air varies with the 
temperature and saturation. This vapor is not always suf- 
ficient to saturate the air with vapor. The ratio of the amount 
contained to that required to saturate the air at the temper- 
ature considered is called the relative humidity while the actual 
amount of vapor per cubic foot is known as the absolute humid- 
ity. Thus at 75° F. air may contain 0.00135 lb. or 9.5 grains 
of water vapor per cubic foot. This quantity will just sat- 
urate it. If the air is half saturated or the relative humidity is 
50 per cent the quantity of water vapor is 4.75 grains to the 
cubic foot. 

In addition to the above substances there may be impur- 

20 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 21 

ities given off from persons or processes and these are variable 
quantities depending on the particular place and time. 

For general work, the air will be assumed to contain 79 
parts of nitrogen by volume, 21 parts of oxygen, 4 parts in 
10,000 of CO2 and a variable amount of water vapor. 

The amount of fresh air to be taken into a room depends on 
the permissible amount of CO2 allowed. It is estimated that 
20 cu.ins. of air is inhaled at each respiration and there are about 
20 respirations per minute, making about a quarter of a cubic 
foot of air per minute. The CO2 in this respired air amounts 
to about 4 per cent so that the respired air has its CO2 content 
increased 100 fold from 4 parts per 10,000 up to 400 parts. 
Although the CO2 is heavier than the air, ha\dng a molecular 
weight of 44 while the air has a weight of 28.9 it diffuses through 
the air and forms a mixture of air and CO2. This foul air is 
then diluted by the air in the room and the condition of the 
air in the room is raised to x parts of CO2 per 10,000 parts. If 
V is the volume of the air allowed per person per hour, the 
equation showing the value x would be 

4F 4ooXiX6o _ xV , V 

lOOOO loooo loooo' 

If the quantity of air respired per minute is changed from 
that assumed and if the quantity of CO2 in the exhaled air is 
not 4 per cent for actual conditions, other values can be used 
in the equation. The equation reduces to 

, 6000 . V 

^ = 4 + -y-, (2) 

or 

F = ^°. (3) 

X-Ar 

Formula (3) gives the quantity of air per hour if the allowable 
quantity in vitiated air x is known. Formula (2) gives the 
quality of vitiated air if V is known. According to Pettenkofer 



22 ELEMENTS OF HEATING AND VENTILATION 

the amounts of CO2 per hour developed by a strong workman 
at work is 1.275 cu.ft. while at rest it is only 0.825 cu.ft. These 
are higher than the amount assumed above. Scharling gives 
0.635 cu.ft. as the amount of CO2 per hour produced by men. 
This agrees with the assumption made above. The other 
values of CO2 exhaled per person, given by Scharling are as 
follows : 

Women 0.600 cu.ft. per hour 

Young men 0.614 

Young women. . o-455 

Boys 0.363 

Girls 0.343 



( ( C I i i 



C ( I C i i 



The presence of 11 parts of CO2 per 10,000 in air when the 
increase has been due to respiration is found to be oppressive 
and harmful. In cases of gatherings of healthy persons this may 
reach 15 parts while with sick, it should be kept as low as 7 
parts. Some claim that it is the other gases or organic mat- 
ters which are exhaled which cause this air to be harmful. The 
lungs and the moistened mouth and nostrils must allow saHva 
and other fluids to be discharged in the forms of vapors and. 
these with any bacteria exhaled contaminate the atmosphere. 
It may be that the CO2 is merely an indicator of the other harm- 
ful constituents in the atmosphere of rooms which are poorly 
ventilated. When the CO2 content is about 7 parts to 10,000 
there is no evidence of discomfort and this may be taken as the 
limit of X for proper ventilation. Eq. (3) then gives 

,^ 6000 r. 1 

V = — — =2000 cu.ft. per hr. 

7-4 

This value is usually employed for the proper ventilation 
of buildings, 2000 cu.ft per person per hour. In cases where 
the number of persons is not definite it is customary to express 
the amount of air in terms of the number of times the volume 
of the rooms is changjed per hour. 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 23 

Rietschel recommends the following amounts: 

Table of Cubic Feet of Air per Hour per Person 

Max. Min. 

Hospitals for adults 2650 2650 

Hospitals for children 1 240 1 240 

Schools, children under 10 years 600 353 

Schools, children over 10 years 885 530 

Waiting-rooms with known number of people .. . 1240 706 

Auditoriums with unknown number of people ... 2 changes i change 

House rooms in constant use 4 changes 3 changes 

House rooms in occasional use i change | change 

Kitchens and toilet rooms 5 changes 3 changes 

When the number of persons is not known some designers 
use the following when provisions are made for changing the air : 

Residences: Halls, 3 changes 

Sitting rooms, and ist floor rooms, 2 changes 
. Sleeping rooms and 2d floor rooms, i change 
Stores: ist floor, 2 to 3 changes, 2d, i| to 2 changes 

Offices: ist floor, 2 changes; 2d, i| changes 

Churches and public assembly rooms, f to 2 changes 

When no provisions are made for ventilation, leakage will 
cause about tV of the above changes. Experiments have been 
made to show that this leakage actually does take place. 

The following allowances are to be used: 

For Adults per Hour per Person 

Hospitals 2400 cu.ft. 

Auditoriums 2000 ' ' 

Workshops 2000 ' ' 

Waiting-rooms 1000 ' * 

For Children 

Hospitals 1500 cu.ft. 

Schools 1500-2000 * ' 

Auditoriums 1500 ' ' 

Workshops 1500 ' * 

As gas flames give off CO2, moisture and other gases, the use 
of gas burners in a room contaminates the air and requires addi- 
tional air for ventilation. If a gas contains by volume 10 per 
cent carbon monoxide, 2 per cent carbon dioxide, 30 per cent 
methane, 4 per cent C2H4 and the remaining gases do not con- 
tain carbon, it will be found that the burning of one cubic 



24 



ELEMENTS OF HEATING AND \^NTILATION 



foot of gas will produce J cu.ft. of CO2, if reduced to the initial 
temperature and pressure. The amoiuit of CO2 exhaled per 
hour per person equals 4 per cent of the air used which amounts 
to about 4 per cent of 15 cu.ft. or 0.6 cu.ft. The amount of con- 
tamination of the ordinary Welsbach mantle burner using 




Fig. 15. — Pettersson's CO2 Apparatus. 

3 cu.ft. equals that produced by two persons, while the fish-tail 
burner, using 5 cu.ft., is equivalent to four persons. Carpenter 
states this thus: The burning of i cu.ft. of gas per hour re- 
quires the amount of air equal to that required for one person. 
The amount of CO2 in the air in most cases is so sKght that 
the ordinary gas apparatus cannot be used to determine it. 
A form due to Pettersson is used. The tubes A , B and C are 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 25 

immersed in a water bath to equalize the temperature. By 
lowering and raising the mercury bottle D, the caustic potash is 
sucked to the mark on the capillary tube below the cock F and 
then tube A is exhausted of air through the cock E. The air to 
be tested is then drawn into A to the small tube M at the 
bottom which is graduated. While this is being done I and H 
are open. After closing these and the cock E, and bringing 
the mercury in D and A to the same level, the cock G is open 
and the position of the hquid drop at K is noted. G is then 
shut off, F opened and the air is driven over into the burette C 
where it comes in contact with the KOH on the glass tubes, the 



II II 


( 


\ 


=— ] 


E=^ 




Fig. i6.— CO2 Bottle. 

KOH is driven into the vessel L. This is repeated several times, 
then the air is driven into A until the KOH fluid reaches the 
same mark below F when F is closed. G is opened and D is raised 
or lowered until the drop K is at the original scale reading. 
This means that the pressure on the gas in ^ is the same as 
before. The reading on the scale M then gives the diminu- 
tion of volume or the amount of CO2 absorbed. The small 
tube M permits one to determine small absorptions and the 
drop K gives an accurate method of getting the correct pressure. 
A simple apparatus for getting relative results is shown in 
Fig. 16. The bottle is filled with a standard solution of 
sodium carbonate and phenolphthalein. If CO2 is introduced 
into this until there is sufficient to change the sodium carbonate 



26 ELEMENTS OF HEATING AND VENTILATION 

into the bicarbonate, the pink color is destroyed and the solu- 
tion becomes colorless. If now it takes A volumes of the bulb 
to destroy the color when atmospheric air is used and B volumes 
for the same amount of the same liquid when taking air from a 
room, the number of parts per 10,000 in the air of the room will 

be ^. Billings gives the strength of solution to be 5.3 grams 

of desiccated sodium carbonate, i gram of phenolphthalein 
and 1000 c.c. of distilled water which has been recently boiled 
and cooled. When ready to use, this is diluted still further with 
twenty-five times its volume of boiled distilled water.* 

The amount of moisture in the air is another important 
item to consider in connection with the air for ventilating pur- 
poses. If the relative humidity is low, evaporation will take 
place from the surface of the body producing dry skin or dry 
mucous membrane in throat or nose and at the same time the 
temperature of the body will be lowered due to this evaporation. 
If on the other hand the air is saturated the body will feel damp 
and clammy. In either case the air is objectionable. The 
usual amount of moisture to make the room comfortable should 
be such as to give a relative humidity between 60 per cent and 
80 per cent. 

To determine the amount of moisture in air, hygrometers of 
some form are used. One method is to reduce the air or a sample 
of it to such a temperature that it will become saturated or 
deposit moisture. Fig. 17 illustrates one form of dew-point 
apparatus or hygrometer in which the aspiration of air through 
a volatile liquid reduces its temperature so that moisture begins 
to form on the silvered surface at the lowered end of the appara- 
tus. The temperature at which this forms can be noted and 
again the temperature at which the moisture just disappears. 
The mean gives the temperature of saturation or the dew-point. 
The weight of moisture (or steam) per cubic foot at this tem- 
perature, from the steam tables gives the quantity of moisture 
present per cubic foot at actual temperature. This will be the 

* Lunge to whom this method is due does not find the exact proportion 
and gives a proportional table of number of volumes of bulb and amount of CO2. 



AMOUNT AND CONDITION OF AIR FOft VENTILATION 27 



amount of moisture per cubic foot in the original air except for 
the slight reduction of volume due to the change of absolute 
temperature; hence if the weight of steam for the given tem- 
perature of the original air is divided into the actual weight 
the result is the relative humidity. 

This form of apparatus is difficult to use and for that reason 
the wet and dry-bulb hygrometer is used. This consists 
of two thermometers on one of which a piece of wet wicking 



■°* 






o 



\^ 



D 



1 



I 



e: 



Fig. 17. — Dew Point Apparatus. 



Fig. 18. — Sling Psychrometer. 



encases the bulb. As water is evaporated from this wicking 
the temperature is lowered and the thermometer reads lower 
than the dry-bulb thermometer. This action is not regular 
if the thermometer or air is at rest and hence the U. S. 
Weather Bureau recommends whirling these thermometers. 



28 ELEMENTS OF HEATING AND VENTILATION 

Fig. 1 8 shows the appearance of this type of instrument. It is 
sometimes called a sling psychrometer. 

Experiments have been made comparing readings of the dry 
bulb and difference between wet and dry bulb with the relative 
humidity readings obtained by a dew-point apparatus. From 
these Ferrel has reduced for the U. S. Weather Bureau the 
following formula: 

^ = ^i-o.ooo367B(/-/i)[i+o.ooo64(/i-32)]. . (4) 

In this expression p is the pressure of the water vapor at the 
dew point, pi the pressure at the temperature of the wet bulb, 
B the barometric pressure, t the temperature of the dry bulb in 
degrees Fahrenheit and ti the temperature of the wet bulb in 
the same imits, p, p\ and B are measured in the same units, 
pounds per square inch, inches of mercury or by other unit. This 
formula contains the quantity B and hence all humidity charts 
and tables based on the formula are worked out for the standard 
atmospheric pressure of 29.92 ins. of mercury and corrections 
must be applied for other barometric pressures. If p is found by 
this formula, the weight of steam per cubic foot at this pressure 
and temperature may be found from the steam tables. The 
number of cubic feet of air for a given weight at the temperature 
t will be greater than that at the dew point ta, and therefore the 
steam will occupy m^ore space. If Wsp is the weight of a cubic 
foot of steam at the dew point, the weight in a cubic foot at 
the temperature t will be 

Wsp{ta-]-AS9-^) 



/+459.6 



(5) 



In the above the air pressure is practically constant. If Wst 
is the amount of steam per cubic foot required to saturate 
the volume at the temperature /, the relative humidity will be 
given by 

TF.(/+459-6) 

Now since the pressure p is the partial pressure due to the 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 29 

moisture present, the ratio of this to the saturation pressure 
will give the same value practically or 



relative humidity = — . 



(7) 



Difference between Wet and Dry Bulb 
r 34° 30° 26°24 20° 16° 12°10° 8° 6° 4" 2°- 




0.40 1 0.60 

Relative Humidity 



Fig. 19. — Relative Humidity and Moisture for 30.3 ins. Barometer. 



Diagrams, Figs. 19 to 22, give relative humidities and weight 
of moisture per cubic foot of air in grains figured from this 
formula for barometric pressures of 29.1 ins., 29.5 ins., 29.9 ins., 
30.3 ins. of mercury. Another instrument shown in Fig. 23, 



30 



ELEMENTS OF HEATING AND VENTILATION 



known as the hydrodeik (as made by the Taylor Instrument 
Co.) employs a graphical chart by which relative humidity 
and other psychrometric data can be obtained. 

The sliding pointer on the arm pivoted at the top is set 



am 



130 



no 



Difference between Wet and Dry Bulb 

48° 40° 36° 32° 28° 24° 20° 16° 12° 10° 8° 6° 4° 



2- 



90 



TO 



50 





\v 




■ 


W 




W~' 


"^ 


\ 


w 


yJlrilm 


ml 


m 






n K, 


- 




w 




'm 


M 


m 






ilnr 


~-~ 




M 




m 


'l/ffj 


m] 






Ijfr 


---; 


/ X /\/ 


% 




M 


Wi 


ul 






n^- 


^ r 




^ 




m 


%^ 


/fjy 






fnr 






M 




W/ 


V// 


y// 






Ulr 




i 


^ 




W/, 


i 


^ 






JJi] 


^1 




M 


/ y\/ 


^ 




?// 






7i 1 


< 




^ 


s^ 


^ 


^ 


'// 


/ ** 


'/ / 


'11 


■-! 




^<^ 


i 


y^ X 

^ 




v^ 






/ r 










> 


K 


y 






Al 


:=^2 



0.20 



0.40 1 0.60 

Relative Humidity 



0.80 



70 



15 



10 



1.00 



Fig. 2o. — Relative Humidity and Moisture for 29.9 ins. Barometer. 



opposite the reading of the wet bulb and is then swung over 
until it intersects the lines running down from the dry-bulb 
readings. These are in red on the apparatus. The reading at 
the bottom of the pointer will then be the relative humidity. 
The heavy black lines running up from the dry-bulb side give 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 31 

the dew point if the one passing from the point of intersection 
of the pointer with the down Hne from the dry bulb is followed 
down to the dry side. At the upper end of these lines where 
they cut the down line from 120° F. will be found the number 









50' 


DifEerence between Wet and Dry Bulb 

t0° 36° 32°28°24° 20°18°16°14°12°10° 8' 6° 


t" 2- 


. 


150 


\v 


\ 


NJIh 


J 1 1 1 


Wim 


mmii 


m^- 


^70 




w 


\ v 


nil 1 


rJ 


Ijimu 






Wi ^^ 


^ 60 


130 


\\ 


\m 


Ifffj 


m 




1 










^50 




I / A/ / 


/\l / 1 


/\i 1 / 1 




'//// 
















/vaX/ 


' rJ / 


1 JirL 




-///// 










^40 






//yy) 


' /hi 


Jl 


■Wmiw 












110 


M 


m 


Wi 


ml 




mn 








[f 




"-30 




x// 


w^ 


^J//fi 














b 

fi90 




/VV 


f/y// 


frJ / 1 














^ on 




w 


m 


m 














^^•IS 




/\/ / / 


\[ / / / 


/ /\/ / 
















ft 




^ 


W< 


//// 


W/ 




^s/ / 






. 






A 


^^ 


<^ 


W/^ 


///^ 




77S 

III 




/ / 


r^ 


^10 


70 


y//A 


^Cyy 


/(// 


//y 


/ / / 






/ °/ 


W J 


' 




^yy 


/(// 


yy\./ 


/ /}(. 


/ / 






/ 7 










m 


^ 


/y/ 


'/// 


/y^ 












-7 




^ 


^ 


Ya 


■^ 


(// 


/ / 








^' 


-5 


50 


^^ 


y^y^ 


y\y^ 


// . 


'y^\/ 


^ / 












'^'^^ 


.y^ 


^ 


^ 


^ 


^ 


/ y 






f 


-8 


ts\ 


^ 






:> 


k 


/ 








c 


-2 



0.20 



0.40 1 0.60 

Relative Humidity 



0.80 



1.00 



Fig. 21. — Relative Humidity and Moisture for 29.5 ins. Barometer, 



of grains per cubic foot. The Lambrecht Polymeter is an 
instrument consisting of a number of human hairs connected to a 
pointer which gives the humidity because the quantity of moist- 
ure which they will absorb and therefore the amount they will 
change in length is a function of the humidity of the medium 



32 



ELEMENTS OF HEATING AND VENTILATION 



around them. This instrument should be checked constantly 
if used. 

W. H. Carrier has discussed the matter of psychrometric 
formulae in the Journal of the American Society of Mechanical 



Difference between Wet and Dry Bulb 

48° 40°36'32° 28° 24° 20° 16° 12° 10° 8° 6° 4° 2— 




0.40 1 0.60 

Relativ^e Humidity 



Fig. 2 2. — Relative Humidity and Moisture for 29.1 ins. Barometer. 

Engineers for Nov., 1911 (p. 1311), and shows that the tem- 
perature of the wet bulb is such that the lowering of the air and 
water vapor in the atmosphere to this temperature will liberate 
sufhdent heat to vaporize the necessary moisture to saturate 
the air at the wet-bulb temperature. This means that the 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 33 

wet-bulb temperature will be above the dew point. Carrier 
states that this wet-bulb temperature depends on the total of 
the sensible and latent heat in the air and is independent of 
the relative proportions. Using this fact Carrier gives the 
following for i lb. of air, mixed with W lbs. of water; 




Fig. 2s. — Hydrodeik. 
fieat given up in cooling air and moisture 

= {iXC,a+C,sXW)(t-n. . 
Heat received by water at temperature of wet bulb 
= r'{W'-W). ...... 



Cpa = specific heat at constant pressure of air 

= 0.24112+0.000009/; 
Cps = specific heat at constant pressure of steam 

= 0.4423+0.00018/ (approximately) ; 



(8) 
(9) 



34 ELEMENTS OF HEATING AND VENTILATION 

t = temperature of air or dry bulb ; 
f = temperature of wet bulb ; 
W^ = weight of moisture per pound of air to saturate air 
at temperature f; 
/ = heat of vaporization of steam at temperature t\ 

These may be equated giving 

iC,a+C,sW){t-0=r\W'-W). . . . (lo) 

This equation is based on the theory that the heat content 
of the air remains constant and has the advantage of the empir- 
ical equation of Ferrel which does not hold for high temperatures 
which are obtained in kiln or drying sheds. 
Solving the Eq. (lo) for W gives 

r'W'-C,a{t-t') , . 

r'+C,S-t') ■ • • • • ^"^ 

This equation can be used to solve for W the moisture content 
when t and t' are known, for the other quantities can be found. 
It is to be noted that 

w/_ 53-35 X(/^+459-6) . . 

V/ = volume of i lb. of saturated steam at temperature f 
{B—p') = Partial pressure on air in pounds per square inch. 

If W and W are known the drop in temperature due to 
saturating the air is given by 

The amount of water to be absorbed is given by 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 35 
Carrier in addition to these derives the theoretical formula: 

,_(B-£)(^ .... (.5) 

2800—1.3^ 

where t and t' are the dry- and wet-bulb readings and p' is the 
pressure of the saturated steam for the temperature f , B is the 
barometric reading. 

On account of the error in the thermometer readings of the 
ordinary sling psychrometer, Carrier makes 1.6 per cent cor- 
rection, giving the equation 

jB-m-f) 

^ ^ 27ss-i.28i" 

to be appUed with sling psychrometer. If pt is the saturation 
pressure at the temperature /, the relative humidity is 

^ pt pt 2755-1.28^' 

Either Ferrel's or Carrier's method can be used with agreement 
of 2 per cent or 3 per cent until high temperature and large 
temperature differences between wet- and dry-bulb readings are 
found. 

The value of the hygrometer and the psychrometric for- 
mulae resulting from it is in the information it gives us of the 
amount of water vapor contained in the air and hence its con- 
dition for use in a ventilating system or for other service. If 
for instance air partially saturated is brought in contact with 
water finely divided, an evaporation will immediately take place, 
which will cool the air to practically the temperature of the wet 
bulb of the hygrometer. If, on the other hand, cold saturated 
air is warmed in a heater or by a steam coil, the moisture con- 
tained in the cold air is not sufficient to saturate the warm air 
and the unpleasant sensation of excessively dry air is produced 
unless the air is humidified in some way. 

Air which is very warm may be cooled in some processes and 



36 ELEMENTS OF HEATING AND VENTILATION 

the capacity for water vapor may be much less than the actual 
quantity contained at the higher temperature and hence this 
reduction of temperature will cause a precipitation. By finding 
the number of pounds of water vapor per cubic foot from steam 
tables at a given temperature, the result may be compared with 
the capacity at another temperature and the relative humid- 
ity, quantity of vapor to be added or abstracted, or other prop- 
erty of the vapor at the new temperature found. 

The pressure exerted by the water vapor is equal to the 
steam pressure at the temperature considered as given by any 
set of steam tables. This is usually known as vapor tension. 
If the air is not saturated, the pressure is equal to that of the sat- 
urated vapor multiplied by the relative humidity. Thus if 
^s = pressure of saturation and p=the relative humidity, the 
vapor pressure p is given by 

P=9ps (i8) 

A similar formula may be used to find the weight of water 
vapor Yy in i cu.ft. of air, namely 

iv=rts (19) 

Now the volume of i lb. of air is given by the equation 

„, _ 53-35 X(^+459>6) , . 

where ?;a = volume of i lb. of air in cubic feet; 
/ = temperature of air in degrees F.; 
B = barometric pressure in pounds per square inch; 
/> = partial pressure of moisture in pounds per square inch- 
Hence the weight of moisture associated with i lb. of air is 
^.-,,,. _ 53-35 X (/+459-6)Xt. , , 

_ 53-35(^+459>6)XpXy. , . 

i44{B-9Ps) ^''^' 

Y, and ps depend on t. 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 37 

On account of y being such a small quantity when expressed 
in pounds, this may be reduced to grains by multiplying by 
7000. 



Difference in Temperature 
50 42 38 34 30 26 22 18 1412 10 



i 2 




Relative Humidity 
Fig. 24. — Relative Humidity and Moisture According to Carrier's Formula. 



These formulae for the weight of moisture in the air in grains 
are = 



W (per cu.ft.) =7ooop-/s = 7oooYt 



(23) 



W (per lb. dry air) = 7°o°X53.35(^+459-6)p t,_ ^^^^ 

1 44 (5 -p/) J 



38 



ELEMENTS OF HEATING AND VENTILATION 



The relative humidity p and the partial pressure p may be 
found by the charts or the formulae and after these are known 
the weight of moisture may be found for any given condition. 

To aid in computing problems relating to moisture, the 
curves, Figs. 19, 20, 21, 22 and 24 are given, the first four 
using the Weather Bureau formula, the last, from Carrier's 
article in the Journal of American Society of Mechanical Engin- 
eers. Table I is constructed to give certain of this information 
in tabular form. 

Table I 

PROPERTIES OF DRY AIR AND AIR SATURATED WITH MOISTURE 



51 


Weight 

of 
I Cubic 
Foot of 
Dry Air. 


Vapor Tension 

or 

Steam Pressure.* 


Partial Pressure 
on Air. 


Weight of Water 
Vapor in i Cubic 
Foot of Mixture. 


Weight 
of Air in 

I Cubic 

Foot of 

Mixture 

in 

Pounds. 


Pounds 
of Mois- 




Pounds 

Per 
Square 
Inch. 


Inches 
Mercury 


Pounds 

Per 
Square 
Inch. 


Inches 
Mercury 


Pounds. 


Grains. 


ture Per 
Pound 
of Air. 





0.0863 


0.019 


0.038 


14.678 


29.873 


. 00008 


0.6 


0.0862 


. 0009 


10 


0.0845 


0.031 


0.063 


14 


666 


29.858 


0.00012 


0.8 


. 0843 


0.0014 


20 


0.0827 


0.050 


0.103 


14 


647 


29.818 


0.00019 


1-3 


0.0825 


0.0023 


30 


0.0810 


0.081 


0. 164 


14 


616 


29-757 


0.00029 


2.0 


. 0805 


0.0036 


40 


0.0794 


0.122 


0.248 


14 


575 


29.673 


0.00041 


2.9 


0.0788 


0.0052 


50 


0.0779 


0.178 


0.362 


14 


519 


29-559 


. 00059 


4-1 


0.0762 


0.0077 


60 


0.0765 


0.256 


0.521 


14 


441 


29 . 400 


. 00083 


5-8 


0.0752 


O.OIIO 


70 


0.0749 


0.363 


0.739 


14 


334 


29.182 


O.OOI15 


8.0 


0.0731 


0.0157 


80 


0.0735 


0.506 


1.030 


14 


191 


28.891 


0.00158 


II . I 


0.0710 


0.0226 


90 


0.0722 


0.696 


1. 417 


14 


001 


28.504 


0.00213 


14.9 


0.0688 


0.0310 


100 


0.0709 


0.946 


I .926 


13 


751 


27-995 


0.00285 


19.9 


0.0663 


. 0430 


no 


0.0697 


I. 271 


2.588 


13 


426 


27-333 


0.00377 


26.4 


0.0636 


0.0592 


120 


0.0685 


1.689 


3-439 


13 


008 


26.482 


. 00493 


34-5 


. 0606 


0.0814 


130 


0.0673 


2.220 


4.520 


12 


477 


25.401 


0.00637 


44-6 


0.0571 


0. III5 


140 


0.0662 


2.885 


5-873 


II 


812 


24 . 048 


0.00814 


57-0 


0.0532 


O.I53I 


150 


0.0651 


3-715 


7-563 


10 


982 


22.358 


0.01032 


72.2 


. 0486 


0. 2122 


160 


. 0640 


4.738 


9 . 646 


9 


959 


20.275 


0.01296 


90.7 


0.0434 


0. 2987 


170 


0.0630 


5 990 


12.195 


8 


707 


17.726 


O.O1613 


112 .9 


0.0373 


0.4320 


180 


0.0620 


7-5IO 


15.289 


7 


187 


14.632 


0.01993 


139-5 


. 0303 


0.6571 


190 


0.061 I 


9-339 


19.013 


5 


358 


10.908 


. 02444 


171. 1 


0.0223 


1.0974 


200 


. 0602 


11.528 


23.469 


3 


169 


6.452 


0.02974 


208.2 


0.0130 


2 . 2930 



* From Peabody's Tables and Marvin's Results. 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 39 

Humidifiers and Washers 

Another important consideration is that of the cleanliness 
of air for ventilation. Air from the atmosphere near a large city 
is laden with dust particles which will be introduced into build- 
ings, where they collect on furniture, tapestry, walls or on goods 
in the process of manufacture. Moreover this air is not good 
for breathing and hence endeavor is made to cleanse it before 
discharging it into the rooms. 

Several methods have been proposed for this purpose. Fig. 




Fig. 25. — Carrier Air Washer and Humidifiers. 



25 shows that of the Buffalo Forge Co., The Carrier Air Washer 
and Humidifier. After the air passes the tempering coils it 
enters a chamber in which are placed a number of nozzles from 
which on account of the rapid rotation of water within the 
nozzle a spray is formed which fills the chamber. As 
air is drawn through this spray, it collects the dust particles 
and part of them fall to the bottom of the chamber with the 
water, A large part of the moisture and dust particles are 
carried over to a series of vertical plates which are arranged so 
that the air has to take a zigzag course. In this way the mois- 
ture is collected and runs down the surface of the plates to a 
reservoir at the bottom from which it is taken from a settling 



40 



ELEMENTS OF HEATING AND VENTILATION 



chamber through a strainer to a centrifugal pump by which 
it is again taken to the nozzles. 

The Eliminator plates are so arranged with projections that 
the water cannot be carried along by the air. In this way the 
air leaves the eliminator without a trace of free moisture. The 
collection of dust and dirt may be washed out from the collect- 
ing chamber at intervals. 

The degree to which this air is tempered before passing 



fr ■ ^Qp^ 




Fig. 26.- — Warren Webster Washer and Humidifier. 



through the washer and humidifier should be such that the 
moisture content is that desired for air to be used in the various 
rooms. If this air is too hot its moisture content will be so great 
that moisture will condense on being used at room temperature. 
Fig. 26 shows the method used by Warren Webster & Co. 
in their air washer and humidifier. In this apparatus water is 
discharged from a pipe A at the top of the air passage just 
beyond the tempering coils. This pipe is perforated with holes 
arranged in a line but incHned to each other. The discharge from 
these holes, A in. or larger in diameter, strikes against a copper 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 41 

hood as shown. This makes the water fall in a sheet of crossing 
streams, the hood causing each individual jet to spread out 
lengthwise of the pipe. The pipe A is supphed from one end by the 
pipe B and at the other by the equahzer pipe C, which crosses 
over the apparatus. The valves on the pipes B and C are so 
arranged that water may be sent through the spray pipe from 
one end only, the water passing from the other end through the 
equaHzing pipe to D and then to the sewer. In this way the dirt 
which may clog up the spray pipe can be cleaned out. The ends 
of the spray pipe or head are carried by deflecting plates which 
keep the water from coming in contact with the casing and so 
eroding it. After passing a short distance from the second sheet 
of water the air enters the eliminators or baffles E, the window 
F opening into the space in front of the baffles. The eliminator 
consists of two rows of V-shaped plates sHghtly inclined to the 
horizontal so that the water and dirt abstracted from the air 
may drain off at one end. These two rows are found sufficient 
to remove the excess moisture. The main portion of the dirt 
is removed by the sheet of spray and falls to the bottom where 
a metal tank is placed. From this point the water passes through 
a double strainer to the suction of the centrifugal pump and is 
again discharged through A . A float valve is used in the system 
to make up the loss of water to the air. An overflow and a 
drain are connected with the sewer for the purpose of removing 
the dirt at intervals. In some Warren Webster apparatus 
spray nozzles are used in addition to the spray head. 

In most of this apparatus it is well to preheat the air to 40° 
or 50° so as to prevent the formation of ice in cold weather, 
and secondly to have such a temperature that the saturation 
of the air at that point will give the proper relative humidity 
at the temperature of the building. The Warren Webster 
purifier has also a device attached to it such that water is 
heated to about the temperature of the tempered air, thus 
making the air practically saturated at the temperature fixed 
by the tempering coils. This temperature is controlled by 
a thermostat placed in the space just in front of the reheating 
coil. By finding the temperature of the air saturated with vapor 



42 



ELEMENTS OF HEATING AND VENTILATION 



at which the amount of water vapor is equal to that desired in 
the heated air the thermostat is set at this temperature and then 
steam will be admitted to heat the air and water until this 
temperature is obtained. 




Fig. 27.— Cloth Filter. 




Fig. 28.— Whitley Patented Air Filter. 

In Figs. 27 and 28 simple methods of cleaning the air are 
shown. A cheese cloth fabric is placed around a wire cyHnder, 
closing off the inlet of a fan blower. The air is drawn through 
this and deposits its dust or dirt. The dirt is washed from the 



AMOUNT AND CONDITION OF AIR FOR VENTILATION 43 

cloth by revolving the cylinder in a trough of water by which 
it is washed clean. In Fig. 28 the cloth is folded over sticks 
and is hung in folds between the edges of a box. The air in 
passing through the cloth gives up the dirt. In both of these 
the endeavor has been to make the cloth surface as large as 
possible to cut down the velocity. 

The air washer becomes an apparatus for cooling the air 
in the summer time if the humidity of the atmosphere is low, 
as the evaporation of the water vapor will cool the air. It 
practically reduces the air to the temperature of the wet bulb 
of a hygrometer. If the air is saturated with moisture, there 











































n.8n 










































V- 






































So.ro 


s 


K 










































^ 


"-V 
































> 

0.60 










^ 
















































^^ 






















0.^ 
























■""^ 




■ — 












<i' 


5 


r 


(5 


J^ 


7 


r 


8 


r 


9 


0= 


10 


0^ 


n 


0" 


12 


0^ 


13 






Temperature of Inlet Air 
Fig. 29.— Values of K for Various Temperatures. 

will be no decrease in temperature unless the water used in the 
washer is low. In such a case fresh cold water from the city 
supply or a deep well is passed through the washer and dis- 
charged directly into the sewer after falHng to the bottom. In 
this way the water is not heated as would occur if this were 
used repeatedly. This method of cooKng is an important one for 
summer ventilation. Warren Webster & Co. have experimented 
with their apparatus and give a series of curves showing the 
amount of cooling in air of various temperatures and various 
relative humidities when using the water repeatedly and when 
using cold water at various temperatures, allowing the water from 
the apparatus to waste to the sewer. The author has shown the 



44 ELEMENTS OF HEATING AND VENTILATION 

results of their work as an approximate formula. When the 
water is recirculated the drop in temperature is given by 

/itr = K\ta-Ul ...... (25) 

where 4 = temperature of the air in degrees F.; 
twb= " " wet bulb in degrees F. 

K is 3i constant depending on the temperature of the air and is 
given by the curve Fig. 29 A/;. = drop in temperature of air. When 
cold water is used and then wasted, the drop is given by 



= -\ta-t. + -^A, (26) 

24 L 2 J 

/„ = temperature of water in degrees F. 



'A 



CHAPTER III 

LOSS AND GAIN OF HEAT 

Heat being a form of energy, may be measured in any unit 
of energy. In the United States and other Engh'sh-speaking 
countries it is customary to measure it in British Thermal 
Units. (B.t.u.) A British thermal unit is the amount of heat 
required to heat i lb. of water from 62° F. to 63° F. Of 
recent years some authors prefer to use the mean B.t.u., which 
is tIt of the heat required to raise the temperature of i lb. of 
water from 32° F. to 212° F. The second or mean B.t.u. is 
equal to 1.003 B-t.u. 

The French use the Calorie, the amount to raise i kg. of 
water from 15° C. to 16° C. or yro of the amount to raise i kg. 
from 0° C. to 100° C. 

By experiment the relation of these units with the other 
units of energy have been determined and are given below with 
certain other transformation constants: 

I B.t.u. = 778 ft.-lbs. 
I B.t.u. =0.998 mean B.t.u. 
I B.t.u. =0.252 calories 
I calorie = 426.6 kg.m. 
I calorie = 3.968 B.t.u. 
I ft.-lb.= 0.1383 kg.m. 
I kg.m. = 7.2330 ft.-lbs. 
I kg. = 2.2046 lbs. 
I lb. =0.4536 kg. 
I m. =39.37 in. 
I m. =3.2808 ft. 
I ft. =0.3048 m. 
I sq.ft. =0.09290 sq.m. 

45 



46 ELEMENTS OF HEATING AND VENTILATION 

I sq.m. = 10.7639 sq.ft. 
I cu. ft. =0.0283 cu.m. 
I cu.m. =35.31 cu.ft. 
I atmosphere = 14.696 lbs. per sq.in. 
= 29.921 ins. mercury 
= 760 mm. mercury 
= 10,333 kg- P^r SQ- meter 
I kg. per sq.cm. = 14.22 lbs. per sq.in. 
I watt hour = 3.41 B.t.u. 
. =2652 ft.-lbs. 
I cu. liter of mercury = 13.5959 kg. 

I horse-power = 550 ft.-lbs. per sec. 

= 33,000 ft.-lbs. per min. 
= 746 watts 
I horse-power hour = 2546 B.t.u. 
I inch of mercury = 0.49 1 2 lbs. per sq.in. 
I inch of water = 0.036 lbs. per sq.in. 

= 0.58 oz. per sq.in. 
I oz. per. sq.in. = 1.72 inches of water 
I U. S. gallon = 231 cu.in. 

The heat loss from rooms is made up of several parts. There 
are radiation and conduction from walls, windows and doors and 
convection losses due to warming of the leakage air or the air 
for ventilation. The gain of heat is derived from persons or appa- 
ratus used in the room or from sources of light of various kinds. 

The loss of heat through walls partakes of the nature of 
radiation and conduction. The principal loss is made up of 
transmission which is found to depend on the difference of 
temperature and therefore it is similar to conduction rather 
than radiation which depends on a higher power of the tem- 
peratures. The general form in which this heat loss is given is 

H = KA{h-to), (27) 

where A = area in square feet ; 

K = Heat transmitted per square foot per hour per degree 
difference of temperature in B.t.u.; 



LOSS AND GAIN OF HEAT 



47 



ti = room temperature in degrees F. ; 
to = outside temperature in degrees F. ; 
H = B.t.vi. transmitted per hour. 

The value of K depends on several factors: the surface, 
thickness, and kind of material, air spaces and condition of air 
at surface. The following German method from H. Rietschel's 
Leitfaden zum Berechnen und Entwerfen von Liiftungs-und 
Heizungs-Anlagen is useful for future reference for cases which 
have not been calculated in the text. 

The rate of transmission of heat through any substance 
depends on the thickness and 







{^ '3 J*!*" 



'At- 



on the difference of tempera- 
ture. If for instance the wall 
shown in Fig. 30 is made up 
of several thicknesses and the 
temperatures are those marked, 
the equations for the trans- 
mission of heat through each 
section must each give the 
quantity of heat transmitted 
by the wall and these, therefore, 
other. 

The amount of heat conducted by any material per square 
foot of cross-section varies directly with the temperature differ- 
ence and inversely with the length. This gives 



Fig. 30. — Wall Section. 



must be equal to each 



H='j{h-h), 



(28) 



where C is the constant of conduction for i foot thickness in 
B.t.u. per square foot per degree, / is the thickness in feet and 
ti—t2 is the difference of temperature. Using this for the wall 
shown in Fig. 30 the following results: 






J^ih-to"), 



(29) 



48 



ELEMENTS OF HEATING AND VENTILATION 



At the surface of any material there is to be found a temper- 
ature different from that of the space around and it is this dif- 
ference which determines the flow of heat at the surface. If 
a is the coeflSicient of transmission per square foot per 
hour per degree across the surface this becomes at different 
surfaces : 



H = ai{ti-ti) 

= a3{t2 — t2) 

= a4(to —to) 



(30) 



The values of H in the sets above are all the same, hence 
solving for temperature differences and adding, the following 
results: 



H Hh H H HI2 , HI3 H w I // i tfx4 n 

— +— -H 1 |--^-+-7T-H =H — ti -\-ti —t2 +12 

fli Ci a2 ds C2 C3 (14: 

— t2-\-t2 — t2 -\-h —h-\-h~io -\-to —to 

lai Ci a2 as C2 C3 a^j ^ 



(31) 



Now 



hence 



K 



ti — to 



K = 



ai a2 dz ^4 Ci C2 C3 



(32) 



The values of Ci, C2, C3 are found for different substances. 
They are the amounts of heat transmitted for unit thickness 
of material per hour per square foot of surface per degree. The 
experimental values given by Rietschel are quoted below in 
B.t.u. 



LOSS AND GvVIN OF HEAT 49 

Values of C. 

Air, still o . 03 

Brass 61 . 00 

Brickwork o . 46 

Building paper o . 08 

Cement o . 40 

Copper 202 . 00 

Cork 0.17 

Cotton o . 03 

Felt 0.02 

Glass o . 54 

Lead 20 . 00 

Limestone 1.35 

Marble (fine) i .88 

Mortar and plaster o . 46 

Oak. o. 13 

Pine (along the grain) o.ii 

Pine (across the grain) o . 06 

Plaster of Paris o . 34 

Sandstone 0.87 

Sawdust o . 03 

Slate 0.19 

Terra Cotta o • 54 

Tin 3560 

Zinc 74 . 00 

The values of the quantities ai are of the form as given from 
Grashof and Rietschel, 

a = ^+g+ ^^ ^^ ^ (33) 

1 0000 

d and e are constants, d depends on the condition of the air 
around surface and e depends on the material. T is the 
temperature difference between the air and the wall at any 
point. 

To determine the quantity T a method of approximation is 



50 ELEMENTS OF HEATING AND VENTILATION 

used until by practice one knows what to expect. The value 
of the term involving T, 

lOOOO ' 

is small, hence for a first approximation this term may be 
neglected and the value of the various a's may be found. These 
then may be used to find K, 

^ = T^ (34) 



After this is known, the following results: 

K{U-to)=ai{ti-ti') =a2(t2-t2') 
= aiTi = a2To = etc. 

since 



. (35) 



These equations give the first approximation for T. 

In this way after T is found as a first approximation the 
value may be used to determine a second value of a and then a 
new value of T. In this way two or three trials will lead to the 
correct result. 

In any case the value of T is small and this particularly is 
true for thick walls or cases in which U — to is a small quantity. 

Rietschel gives results used in practice for the value of T for 
masonry walls. These may be put into the form of an equation. 

T= 16.2—4.00/ (36) 

This may be used for masonry walls with air spaces where / 
is the sum of the various thicknesses, although this result is 
slightly too large in this case as the quantity K{ti — to) is smaller 
than for a solid wall of the combined thickness. 

For a single glass T is taken as |(^< — while for double 
w^indows \{ti — to) is taken at each surface. Since glass is so 



LOSS AND GAIN OF HEAT 51 

thin there is practically no temperature drop in it. This will 
be seen later. 

The value of T for wooden floors is given as r = i.8° F. 
The values of d as given from Grashof are as follows: 

Values of d. 

Air at rest as in rooms or channels 0.82 

Air with slow motion as over windows i . 03 

Air with quick motion as outside of building i . 23 

The values of the coefhcient e are determined by Rietschel 
as follows : 

Values of e. 

Brass, poKshed 0.05 

Erickwork and masonry o . 74 

Cast iron, new 0.65 

Cotton 0.75 

Charcoal 0.71 

Copper o . 03 

Glass o . 60 

. Mortar and lime mortar o . 74 

Paper 0.78 

Plaster of Paris o . 74 

PoKshed sheet iron o . 092 

Rusted iron o . 69 

Sawdust 0.72 

Sheet iron o-57 

Silk 0.76 

Tin o . 045 

Water i . 07 

Wet glass 1 . 09 

Wool 0.76 

Zinc o . 049 

Wood o . 74 

To explain the application of the above, the wall given in 



52 



ELEMENTS OF HEATING AND VENTILATION 



Fig. 31 will be investigated. The wall is composed of 4 ins. 
of sandstone, 18 ins. of brick work, a 2 -in. air space, 8 ins. of 
brick and i in. of plaster. Where sections of the wall 
actually come in contact, there is no surface resistance and 
the wall may be considered as soHd except for differences in 
the values of C for the various materials. To find a the 




Fig, 31. — Wall Section. 

various values of T must be known; now T is given by the 
following : 

Ti =ti — ti ; 
^3 =^3 —^3; 
Tz =h — h ; 

These quantities vary inversely with the different values of a,. 
since 

aiTi = a2Tz = (i2T^ =a4.To. 

As the quantities a do not differ by great amounts these various 
values of T are considered as equal quantities in comput- 
ing a. 

T may then be found f/tom the equation, 



r= 16.2—4.00/. 



LOSS AND GAIN OF HEAT 53 

In this case the total thickness is 31 ins. and 

r=i6.2-4X — = 6°. 

^ 12 

(42X1.23+31X0.74)6° 
fl^4 = 1. 2^+0.74+ ■ ; 

'^ ' '^ lOOOO 

(42X0.82+31X0.74)6° 



^3=0.82+0. 74 + 
a2 = o. 82+0.74 + 



1 0000 
(42X0.82+31X0.74)6° 



ai =0.82+0. 74- 



1 0000 
(42X0.82+31X0.74)6° 

lOOOO 



^4 = 2.01; 

a3 = i.59 = a2 = ai. 

K is then found as follows : 



K 











I 










I 


I 

1 J 


I 1 


I 

J 


0.33 , 


'•5l 


.017 


1 °-^^ 1 


.007 


2.01 


' 1.58 ' 


1.58 ' 


1.58 ' 


■87 ' 

I 


.46' 


•03 


' 0.46 ' 


.46 



0.497+0.633+0.633+0.633+0.718+3. 26+0.56+1.435+0.037 

I 



8.066 



= .124. 



For a floor or ceiling as shown in A, Fig. 32, the method is 
quite the same. When the high temperature is at the top, 
however, there is no circulation in the air space between the 
plaster and the floor and the air acts as an insulating material. 

When the high temperature is below or if the air space is in 
a vertical position the circulation of the air transmits heat by 
convection and the air does not act as an insulating material 
as was the case with the wall just considered. In any case, 
however, there is a resistance at the surface between the air 
and the partition due to the drop T. 



54 



ELEMENTS OF HEATING AND VENTILATION 



When the same constant does not hold over a complete 
wall or floor owing to a change in the construction as occurs at 
studs in a partition or at joists in a floor, the value of K for the 
whole surface is found thus : 



or 



K{Ai-\-A2){k-to)=KiAi{h-to)+K2A2{ti-to), 



K = 



KiA,-\-K2A2 ^KA 



Ai-^A: 



^A 



(37) 



< < i 





^ Lath and 



A ti" 
Fig, 32. — Wood Floor Construction. 



Blaster 



In most cases the areas A have a common dimension so that the 
areas are proportional to the widths. If these are hi and ^2 
there results (Fig. 32), 



K 



Kibi+K2b2 
bi+b2 ' 



(38) 



The mean constant is not usually found for a wall in terms of 
the glass and wall coefficient as these are kept separate, but there 
is no reason why this could not be done as is the case with 
the coefficient for partitions with partition studs in the cases 
below. • 



LOSS AND GAIN OF HEAT 55 

With the high temperature above the air acts as an insulating 
substance and the following results for the floor, Fig. ^2, A: 

Q , ^ , 42X0.82+31X0.74 o 
a„ = o.82+o.74+ ^^^ 1.8 = 1.57, 

at joists, 

I is.2c; t: I ^' 

+ — + ^ + 

1.57^12X0.06^8X12X0.46^1.57 

« ■ 
at space between joists. 



2^ =.027. 

I 7 2 12 3 51 

757'^i2X8Xo.o6"^iLS7"^i2Xo.o3'^8Xi2Xo.o6"^8Xi2Xo.46"^757 



Combined 



3X0.05 + 13X0.027 
K = ^^- =0.031, 



With the high temperature below on account of the convection 
currents, the air does not act as an insulating substance and the 
following results : 

^ = 1.57; 
^^■ = 0.05; 

Ka = =0.22; 

4 , 1-25 , 5 



1.57 12X0.06 8X12X0.46 
j^ 3X0.05 + 13X0.22 

A= , =0.19. 

16 ^ 

This method may be used for various kinds of walls and par- 
titions. The following values have been computed by the author 
and these values compared with those given by Kinealy, 
Rietschel and others. 



56 ELEMENTS OF HEATING AND VENTILATION 

Values of a. 
For brick and plaster or masonry : 

f^ 4. -A t I 43X1.23+31X0.74 ^ 
Outside a = 1.23 +0.74 + — T 

lOOOO 

= i.97+o.oo75r 
= 2.09 — 0.03/, 
since 

r=i6.2— 4/. 

Inside, a = i.56+o.oo57r 

= 1.65—0.023/. 

For wood and approximately for paper, cotton, wool, sawdust, 
charcoal : 

Outside, a = i.97+o.oo75r = i.98. 
Inside, a = i.56+o.oo57r = i.57. 

For glass : 

Outside, a = 1.83 -1-0.0077 

/^ /i~/o o\ 

= 2.07 (r=— — =35 ). 

Inside with motion. 

a = i.63+o.oo6r 
= 1.83(^ = 35). 
Inside without motion: 

a = 1.42 +0.0057 

= 1.59(7 = 35). 

Inside with motion and wet from condensation: 

a = 2.ii+o.oo8r 
= 2.39. 

For double windows: 

Outside, a = 1.95 (7 = ^X70) 
Center, a = 1.51. 
Inside dry, (2 = 1.74. 



LOSS AND GAIN OF HEAT 



57 




WM/M{'^^^^mmmmiMM^^^^^^^ 



// KWvi /. , 1. s\\\i K\\\\l , ///,\ 



i 



M 






3 -3 :?'3'onfx^^. 

'JD Z'Z _ _^ ~ 33Z'Dj '_u3CUU' 



W////t^$:^^//K\\\\W///i^;^^ 



il 



i 



^^ 



*i 



I 







58 ELEMENTS OF HEATING AND VENTILATION 

Before proceeding with the tabular values an explanation 
will be made of the various common forms of ^building construc- 
tion which are to be found in the following figures. 

Walls. Walls are built in many cases of brick. Bricks vary 
in size in different localities. In some places the dimensions 
are 8JX3J X2J. A standard 8JX4X2} was adopted by the 
national Brickmakers' Association. These are built in various 
thicknesses. At times an air space is made in the wall as shown 
in E, Fig. 33, so that the interior of the wall will be dry and also 
that the wall will be a better non-conductor of heat. When a 
solid wall is built it is not advisable to put the plaster directly 
on the wall as in B, Fig. 33, because the water soaking through 
the wall will produce a damp surface. To prevent this the 
wall, C, Fig. 33, is furred before the plaster is put on. This 
consists in placing wood or iron furring strips on the wall 
and attaching wood or metal lath to these. The wood strips 
are usually f . by 2 ins. so that the laths are removed about 
I in. from the wall, thus giving an air space. The furring strips 
are attached to wooden wedges or plugs driven into the joints 
in the walls. The same effect is obtained by the use of hollow 
bricks, known in some localities as " Haverstraw bricks," as the 
lining of the wall. These are shown at D, Fig. 33. Walls are 
sometimes faced with stone as shown at F, Fig. 33. A recent 
method of wall construction for residences and small buildings 
is to use hollow partition tile and face them with brick or plaster 
as shown in C, Fig. 40. 

Stone and concrete walls are used for buildings and constants 
have been computed for these. 

Wooden walls or frame constructions are used at certain 
times. In this, studs, usually of 2 by 4 in., 3 by 4 in., or 4 by 6 
in. timbers, are placed upright at i6-in centers, and on these are 
nailed sheathing boards, which may be planed boards, although 
at times shiplap as shown in D, Fig. 34, or tongued and grooved 
boards, E, Fig. 34, are used to make tight joints for the purpose 
of keeping down the loss of heat. Building paper of one or two 
thicknesses is then placed on top and the clapboards F, or 
shingles G, are placed on top of this. On account of the frequent 



LOSS AND GAIN OF HEAT 



59 



vertical joints in the shingles these are usually placed so that 
not over one-third of the length of the shingle is exposed to the 
weather. A represents a wall without plaster while B and C 
are plastered on the interior. 

Floors. Floors for dwellings and many small buildings 



S 






p^^^ 






wm. 



^^:^^-^^:->.-V^ 



^ 



:sl 



Fig. 34. — Wooden Walb 



are built as shown in Fig. 32. In this form wooden joists are 
placed on i6-in. centers and on top of them a floor is built 
composed of one or two layers of tongued and grooved floor 
boards or the lower layer may be of shiplap or square edged- 
boards. In any case at least one side of the boards must be 
planed to bring the boards to a uniform thickness. To the 
lower side of the joist, laths are attached and these carry the 



60 



ELEMENTS OF HEATING AND VENTILATION 



plaster. Mill or slow-burning construction, Fig. 35, consists in 
using heavy wooden girders (12 by 12 ins.) about 8 ft. apart 
and on these is a floor of 3 -in. planks. The planks are usually 
of yellow pine above which is placed a hardwood floor covering, 





p^-r^ 


^ 






j 


























^ 




1 — i — ' 


u_ 




/^ 




-^ 








-L-L 




^^^^^^^^^^ 




4^ 














1 L 














1 — 1 


























1 




















1 








1 




^^ v- 



Fig. 35. — Mill or Slow-burning Construction. 

separated by building paper of some kind. Fig. 36 shows a 
fireproof-floor construction using reinforced cinder concrete be- 
tween I-beams. The cinder concrete encases the beams. This is 
reinforced by metal, resting on the beams. The ceiling below 



k»m^m,sm. 


^■-^-■'^--^^^^ 


75j';iiSwS::L-.., 


Z ' • ---^^^^v;'v^^':^^;^^^S^^"■'^^S7.^;■^^^^ 


% 


t/ 




l; 



Fig. 36. — Reinforced Concrete Floor. 



is carried on metal laths attached to small channel irons running 
from beam to beam when a flush ceiling is desired, while at 
times the plaster is attached directly to the concrete, when 
a panel effect is desired. On top of the reinforced concrete a 
lean cinder concrete fill is made between the dovetailed sleepers 



LOSS AND GAIN OF HEAT 



61 



to which the floor boards are attached. The sleeper usually 
runs at right angles to the beams. Two thicknesses of floor 




Fig. 37. — Brick Arches. 

boards are used, the upper surface being of maple when lasting 
qualities are required. 

Fig. 37 illustrates methods of using arch bricks with concrete 




Fig. 38.— Hollow Tile Flat Arch. 

filling. The end voussoirs or skew backs are specially made or 
cut. The brick voussoirs are spoken of as rowlocks when used 
this way. 

Fig. 38 exemplifies the method used with hollow fireproofing 



62 



ELEMENTS OF HEATING AND VENTILATION 



tile. The tiles are made to form a flat arch. The cement 
mortar is arranged in grooves to increase the bonding of the 
tiles. 

A metal lath and plaster ceiling hung from a reinforced 
concrete roof is shown in Fig. 39. 




A— Book Tile. 




B— Roof Tile. 




Fig. 39. — Roof and Roof Ceiling Tile. 



Fig. 39, A , illustrates a book tile and B, a government tile, 
used in forming fireproof roofs. The book tiles are placed so 
that the rounded projecting edges fit into the hollowed edges of 
the adjacent tiles, the square corners resting on the flanges of 



LOSS AND GAIN OF HEAT 



63 



T-irons which are supported by or form the purlins of the roof. 
The tiles are 3 by 12 by 17^ ins. long. The government roofing 
tiles 2f by 12 by 15J ins. rest in the T-irons, the depressed edges 
being so arranged that the bottom of the tile is flush with the 
bottom of the irons. 

Partitions. The horizontal section of the ordinary forms 
of partitions are shown in Fig. 40. A represents the standard 
form of wood partition made of 2 by 4 ins. or by 3 by 4 ins. 
studs of spruce or hemlock placed on i6-in. centers to which 



in 



w 






fc^ 






^^^S:^ 




n 



I 



Fig, 40. — Partitions. 



are fastened wooden or metal laths or a patented sheet substance 
known as plaster board, over which plaster is placed. 

Form B consists of a single row of fireproof tile with plaster 
on each side and C shows two sets of tiles with an air space 
between them. E gives a partition formed of wire lath attached 
to channel irons and D gives one in which expanded metal is 
used to support the plaster while the space on the inside is 
filled with asbestos to ^deaden the sound, as well as to cut 
down air currents and thus cutting down heat transmission. 
The plaster coat in most cases takes up | in. and this may be 
used in figuring thicknesses. The above figures represent 



64 



ELEMENTS OF HEATING AND VENTILATION 



various typical methods of building construction, and the trans- 
mission coefficients which are computed for them will serve as 
guides for other constructions if time is not available for com- 
puting K. 

Values of K. 



WALLS AND PARTITIONS 

(See Fig. 33) 



Combined 
Thickness of 
Brickwork. 


A. 


B. 


C. 


D. 


El. 


E2. 


F. 


4" 

8" 

12" 

16" 

20" 

24" 

28" 

32" 


0.55 
0.39 
0.31 
0.25 
0.21 
0.18 
0. 16 
0.15 


0.51 

0.37 
0.29 
0. 24 
0.21 
0.18 
0.16 
0.14 


0.28 
0. 24 
0. 20 
0.18 
0. 16 
0.14 
0.13 
0.12 


0.29 
0.24 
0.20 
0.18 
0.16 
0.14 
0.13 


0.27 
0.22 
0. 19 
0.17 

0.15 
0.13 
0.12 


0.26 
0.22 
0.19 
0.17 

0-15 
0.13 
0.12 


0.32 
0.20 
0.17 
0.15 
0.14 
0.12 
0.12 



MASONRY 

(Fig. 33) 



Masonry Thickness. 



A. 


B. 


0.54 


0-5I 


0.45 


0.43 


0.39 


0.37 


0.34 


0.32 


0.30 


0.28 


0.24 


0^23 



0.28 
0.25 
0.23 

O. 21 
0.19 
0.17 



CONCRETE 

(Fig. 33) 



Concrete Thickness. 



12" 
18" 
24" 
30" 
36" 
48" 




LOSS AND GAIN OF HEAT 



65 



Wooden Walls 
Fig. 34. 



( Fig. A, 0.31 
i Fig. B. o. 20 
[ Fig. C, 0.08 



PARTITIONS 

(Fig. 40) 

Fig. A. Plaster, one side 0.49 

Fig. A. Plaster, two sides 0.36 

Fig. B 0.30 

Fig. C 0.21 

Fig. D 0.21 

Fig. E 0.34 

FLOORS AND CEILINGS AND ROOFS 



Heated Room 
Above. 



Heated Room 
Below. 



Fig. 32 

Fig. 35 • 
Fig. 36 . 
Fig. 37 
Fig. 38. 
Fig. 39- 
Fig. 39- 



I With plaster . . . 

' Without plaster . 

With plaster . . . 



B 



[ Without plaster. 



With ceiling 

Without ceiling 

Book tile with wood sheathing 

Fig. 39. Government tile \\ath wood sheathing 

Shingle roof, with no sheathing 

Shingle roof, on sheathing 



Glass 

Single window (|") 

Double window (fO . 
Single skylight (i") 
Double skylight (f") 
Doors . 

f" doors 

i" doors 



I Dry 
1 Wet 



doors . 



0.031 

0-33 

0.030 

0.23 

o. 16 

0.025 

0.25 

0.029 



0.96 
1 . 10 
0.41 
1 .06 
0.51 

0.55 
0.48 
0.40 
0.34 



o. 19 

0-33 
o. 16 
0.23 
o. 16 

0-I5 
0.25 
0.14 

O. 22 
0.42 
0.25 

0-35 

0.42 
0.31 



The area A of the conducting and radiating walls or parti- 
tions is found from the plans of the buildings. The total area 
of each side of the room is first found and these are kept separate 



66 ELEMENTS OF HEATING AND VENTILATION 

and called north wall, east wall, south wall and west wall. The 
glass and door area in each of these walls is found and the results 
added together. This sum is subtracted from the wall area and 
then the difference is known as net wall area. The door area is 
considered to be equal to a window in radiating value because 
of its repeated opening and closing. The author usually takes 
the full window frame area as window area in making these 
computations. This allows for the loss of heat due to leakage 
around the frames. The floor and ceiling areas are also com- 
puted at this point for the determination of heat losses. 

Temperatures of Rooms and Atmosphere. In figuring U 
and /o, the temperatures on the two sides of a wall, it is well to 
remember that the use for which the room is intended fixes one 
of these and if the wall is an outside one the other, to, is fixed 
by the lowest temperature which may continue for several days 
or for a week. In the latitude of northern New York U may be 
taken as o° F. or it may be — io° F., while in New York City, 
io° F. or 20° F. may be used. In Washington 20° F. or 30° 
F. might be used. In most contracts the specifications call for 
sufficient installation to heat the building to a desired temper- 
ature in zero weather, but it seems that this should not be used 
in design unless zero weather is found for several consecutive 
days in the locality considered. 

The temperature h depends on the use of the room. In 
general living rooms, offices, schoolrooms and other places 
where persons may be seated in small numbers with wraps 
removed, the temperature is taken as 70° F., while for halls a 
lower temperature is used and for churches where street clothes 
are not removed a temperature less than 70° is used. This 
also applies to places where muscular exercise takes place. The 
following temperatures, averaged from several authors, are 
recommended : 

Warm air baths 122° F. 

Steam baths 113° F. 

Massage rooms 77° F. 

Hothouses 77° F. 

Bathrooms 72° F. 



LOSS AND GAIN OF HEAT 67 

Hospital rooms 72° F. 

Houses, offices, schools 70° F. 

Sewing rooms . . 70° F. 

- Laboratories where observers are seated and 

physically at rest 70° F. 

Lecture halls, auditoriums 66° F. 

Prisons 65° F. 

Shops for Hght work 64° F. 

Churches 64° F. 

Sleeping rooms 60° F. 

Entrances, corridors 60° F. 

Laboratories with engines 55° F. 

Gymnasiums, workshops 55° F. 

When rooms are not heated the radiation from other rooms 
gives heat sufficient to bring them to a temperature above 
the surrounding air, The following are quoted from Kinealy 
as used by German engineers: 

Cellars and rooms kept closed 3 2 ° F. 

Rooms often open to outside as vestibules. . . 23° F. 

Attics under metal or slate roofs 14° F. 

Attics under tile, cement or tar and gravel roofs 23° F. 

The temperature of garrets may be computed better by 
equating the heat loss through the roof to the heat gain from 
the floor to the attic. This gives 

KcAc{ti-ta)=KrAr(ta-to) (39) 

The only unknown is /«, and this m^ay be readily computed. 
The author would recommend the following : 

Cellars 36° F. 

Vestibules 20° F. 

Attic under slate roof 25° F. 

Attic under booktile and metal roof 40° F. 

Attic under wood and metal roof 32° F. 



68 ELEMENTS OF HEATING AND VENTILATION 

The above temperatures of rooms for various purposes are 
the temperatures found about 5 ft. from the floor and may 
be used as the average U for rooms which are not over 10 ft. 
high. When the room is higher than this the average tempera- 
ture' U is higher than the values in the table. According to 
Rietschel the values / are those desired at head height, and the 
mean temperature U must be such that 

ti = t-\-o.oi']{h — io)t (40} 

ti never exceeds 1.15/; 
i^ = desired temperature head high; 
h = height in room ; 
/< = mean temperature. 
If 4 = temperature at ceiling, 

/c = /+o.o35(A — 10)/ (41) 

Having found the mean temperatures of each room or space 
in a building as well as the floor and ceiling temperatures of high 
rooms, these temperatures should be marked on the plans in each 
room. 

Effect of Exposure and Intermittent Heat. The constants 
of transmission are those found in rooms which are not exposed 
to violent winds and are heated continuously. When the room 
is exposed a percentage is added to the quantity found and if 
the building is heated intermittently a similar method is used so 
that the building may be heated in a reasonable time. The fol- 
lowing averages of the allowances made by various authors are 
suggested: 

For north walls add 15 per cent 

For east or west walls '^ 10 

For corner walls '' 10 

For rooms exposed to winds ^' 15 

For heating during day and building closed at 

night ^' 10 

For heating during day and open at night ''30 '' 

For heating occurring at long intervals '' 50 '* 



LOSS AND GAIN OF HEAT 89 

These allowances for occasional heating may be reduced if time 
is available for heating the building, say lo to i8 hours. 

Heat Loss through Walls. The various factors K, A, and 
(ti — to) now being known, the heat loss from the four walls, floor 
-and ceihng of any room may be found by the equation (27). 

A very simple equation for rapid calculation is one due to 
Professor R. C. Carpenter and is often spoken of as Carpenter's 
Rule. This is 

H = (G+iW+o.o2V){h-to) (42) 

H =B.t.u.'s to be supplied per hour; 
G = glass surface in sq.ft. 
TF = net exposed wall area in sq.ft.; 
V = volume of air supplied per hour 

= nv where w = No. of times air in room of volume v cu.ft. 
is changed per hour. 

This gives a rapid method of estimating the amount of heat 
to be supplied. 

Heat for Ventilation. If V is the number of cubic feet of 
air per hour introduced into the room from a temperature to 
and raised to a temperature tt the amount of heat required for 
this will be 

pV 
H, = ^jrCp(ti-to) (43) 

This becomes under general conditions, 

x4.7X144X.24 
53.34X(7o+46o) 

= o.oiSV{ti-to) (44) 

In this 0.018 is therefore the amount of heat to raise i cu.ft. 
of air at 70° F., 1° F. at constant pressure. This quantity for 
rough calculations may be considered as 0.02. The quantity 



70 ELEMENTS OF HEATING AND VENTILATION 

Hv is the amount of heat required to warm the air to room tem- 
perature and represents the amount of heat necessary to warm 
the air which may enter by leakage; or if the air escapes at room 
temperature it represents the amount carried out by that air 
above the heat in the air at the temperature to. 

It is not necessary in finding the heat required to warm the 
ventilating or leakage air, to consider the air as having a higher 
temperature than U, because the air is supposed to leave at this 
temperature, the higher temperature at which the air entered 
the room being decreased to that of the room by the heat loss 
from the walls, and the amount for the change of temperature 
to that of the room is equal to the heat loss from the walls. 
If the amount of heat to warm V CM.it. of air from t2 to h is 
required, this is approximately given by 

^a = O.Ol8F(/3-/2) (45) 

If the V is measured at h = 120° F. instead of 70° F. the constant 
0.018 would truly be 0.0165. In using this value, 0.018, it is 
well to remember that it applies only when V is the volume 
considered at 70° F. 

Heat Given Out by Persons, Lights, Motors, etc. The 
amount of heat given out by persons working or sitting in a 
room, although not so important when only a few are present, 
is of genuine importance when a number are to be considered. 
The following average values may be used: 

Adult at rest 380 B.t.u. per hour 

Adult at work 470 

Adult at hard work 550 

Adult, in old age 360 

Infant 63 

Child 240 

For electric lighting: 

SS000X60 ^ 

I Watt hour — -tt: — =34i B.t.u. 

746X778 ^^ 



LOSS AND GAIN OF REAT 71 

For gas lighting: 



I cu.ft. natural gas looo B.t.u. 

I cu.ft. illuminating gas 700 

I cu.ft producer gas , 150 

I Welsbach burner uses 3 cu.ft. per hour. 
I Fish-tail burner uses 5 cu.ft. per hour. 

For motors : 

Motors used in a room for tools or apparatus of various 
kinds turn eventually all of the power input into heat which 
remains in the room, hence, 



I K.W. hour supply = 3410 B.t.u. 
iH.P. " " =2546 " 



It is important to realize that the power developed to drive 
all machines is turned into heat provided that all of the energy 
is used in a room. This heat may be an important item in heating 
a shop containing a large number of tools. 

Equivalent Temperature. When a given temperature Td 
may be obtained in the room of a building, if the atmospheric 
temperature is Ta, it is often necessary to know if this is equiv- 
alent to a temperature of Tg for the rooms when the air 
temperature is Tag these being the guaranteed conditions. Now 
for direct radiation, the loss equals the heat given by the radia- 
tors. This means, 

(Au,K^-\-AgKg+o.o2V){T,-Ta)=KAr(Ts-T,) . (46) 
and under guaranteed conditions, 

{A^Ku^+AgKg-ho.o2V)(Tg-Ta,)=KiAr{Ts-Tg) . (47) 
Dividing these the following result : 

Tj,— Ta ^ K^ Tg — Ti, . . 

rT ~ TT T T ' • • • • \40/ 

g — lag JS^i 1 3 — 1 g 



72 



ELEMENTS OF HEATING AND VENTILATION 



Now Ki is practically the same as K, and if it is so considered 
the following is found : 



Ts[T, + Ta-Tao]-TaT, 



(49) 



For an indirect system the equation becomes 



^9 J- ag ]7-'\ J" J- agn-J- n 



[t.-'--^] 



(so) 



In this case K^ and K will differ more than in the previous case, 
but if the actual conditions and guaranteed conditions are not 
far different these two quantities may be considered equal, and 
the expression for Tj, is the same as given above. 

This is given in a table below for zero outside weather in the 
guarantee and steam at 5 lbs. gage pressure. 

EQUIVALENT INSIDE TEMPERATURE 



Actual 




Guaranteed inside Temperature. 


Outside Temperature. 


50 


60 


70 


80 


— 10 


42.2 


52.6 


63.1 


73-5 





50.0 


60.0 


70.0 


80.0 


10 


57.8 


67.4 


76.9 


86.5 


20 


65.6 


74.8 


83.8 


930 


30 


73-4 


82.2 


90.7 


99-5 



CHAPTER IV 

RADIATORS, VALVES AND HEAT TRANSMISSION FROM RADIATORS 

Radiators are of various forms. Some are made of cast 
iron or pressed steel and some are made of wrought-iron pipe. 




Fig. 41. — Peerless Three-column Radiator, 

The common form of cast-iron radiator, Fig. 41, is made by con- 
necting several cast-iron sections together by close threaded 
right and left nipples as shown in Fig. 42, or by using conical 

73 



74 ELEMENTS OF HEATING AND VENTILATION 

ended thimbles which are held in place in the sections by means 
of the bolts. The nipples are made with a projection on the 
inside so that they may be turned by a bar which forms a plug 
wrench. The sections are made of various heights from 13 
to 45 ins., and in order to give varying amounts of heating 




Fig. 42. — Section of Loops Showing Nipple. 

surface they are made of various widths. The widths are 
changed by increasing the number of tubes forming single 
column, two colimm, three column, or four colimm radiators. The 
design of the exterior of these radiators is varied to suit different 
architectural requirements. Figs. 41, 43, 44 and 45 illus- 
trate different styles of various typical radiators made by the 
American Radiator Company. 



RADIATORS, VALVES AND HEAT TRANSMISSION 



75 



These radiators are connected at the lower end of each 
section for steam work, while for hot-water systems the sections 
are connected at the top and bottom as shown in Fig. 46. The 
purpose of this is to aid in the circulation of the water by bring- 
ing it in at the top and distributing it to the various sections 




rTTTTm 




Fig. 43. — Peerless Single Column 
Radiator. 



Fig. 44. 



-Rococo Two-column 
Radiator. 



which act as down-takes. This figure illustrates the method 
of constructing these radiators when it is desired to have the 
floor Hne clear. The leg sections are not used in forming the 
radiator and the radiator is held by a bottom support and top 
guide, Fig. 47. 

At times the sections are so constructed that they form, 
by projecting fins or webs, a series of closed passages between 



76 



ELEMENTS OF HEATING AND VENTILATION 



sections. Such radiators, Fig. 48, are known as flue or box 
radiators. This form is used in the direct-indirect system of heat- 



r^'TtTTTn^ 




Fig. 45. — Rococo Four-column 
Radiator. 




Fig. 46. — Hot Water Radiator on 
Brackets. 




TOPGUIDB 




3-OTTO.M SUPPORT 



Fig, 47. — Brackets for Wall Radiators. 

ing, shown in Fig. 6, in which it is desired to draw in a certain 
amount of air for ventilation. 




Fig. 48. — Fiue Box Base Radiator. 




Fig. 49, — Stairway Radiator. 



77 




Fig. 50. — Corner Radiator. 




Fig. 51. — Circular Radiators. 



78 



KADIATORS, VALVES AND HEAT TRANSMISSION 79 




STYLE A 




STYLE B 



Fig. $2- — Rococo Wall Radiators. 




Fig. 53. — Dining Room Radiator. 



80 



ELEMENTS OF HEATING AND VENTILATION 



The heights of the radiators are selected to fit the particular 
positions in which they are to be placed. Usually it is well to 
have them lower than a window sill in front of which they are 
to stand. At times they are put beside the jib panel of a stair- 
way, and in such a case a number of different sizes may be 
united to suit the steps. Fig. 49 is one of this form. Low 



^^^-^^ \^l 






- ^ 














<^ 


-^\ ^ \ 1 





Fig. 54. — Plate Warmer or Pantry 
Radiator. 



Fig. 55. — Detachable High 
Leg Section. 



radiators are made of such dimensions that they may be placed 
under window seats, and in these cases they are known as window 
radiators. 

When a comer radiator is to be placed in a room, Fig. 50, 
or is to be made circular to fit around a column, Fig. 51, special 
sections are made and joined together to form these. These 
may be placed where they are needed for architectural effects; 



RADIATORS, VALVES AND HEAT TRANSMISSION 81 

they are not often used. In most cases the circular radiator 
is made in halves. 

The radiator shown in Fig. 52 is known as the Rococo wall 
radiator, and this type is employed when Kttle space is available. 
The sections are made so that they may be joined at the various 
corners and by making various combinations of elements, dif- 




-a 

Fig. 56. — Radiator Foot Ups. 



ferent shaped spaces may be filled. These radiators are made 
of the following dimensions: 



Section No. 


Length. 


Width. 


Thickness. 


Area. 


5^ 


i6f ins. 


I3r5 ins. 


2| ins. 


5 sq.ft 


7^ and 75 


2I| " 


I3A " 


2I " 


7 " 


gA and gB 


29^" 


13^ " 


A " 


9 " 



These are the over all dimensions of the section, and various 
sections may be so connected by nipples that they come together, 
iron to iron. 

Radiators may be joined together forming a sort of cup- 
board, giving a so-called dining-room or pantry radiator, Fig. 
53. Plate warmers. Fig. 54, may be constructed by using wall 
radiators. 

The leg loops of radiators are sometimes made with a 
detachable leg. Fig. 55, so that in mo\'ing carpets the leg at 



82 ELEMENTS OF HEATING AND VENTILATION 

one end may be removed and then at the other. The radiator 



-1 CZ 

Fig. 57. — Pedestals. 



HD 



foot 



© 




'^'T^ 




Fig. 
are \ 



ups, Fig. 56, may be used for the same purposes. Radiator 

pedestals, Fig. 57, may be used 
to raise the radiator from the 
floor an additional distance when 
necessary. 

Fig. 58 gives the appearance 
of the Kinnear pressed steel 
radiator. The radiators are light 
and will not crack. They are 
giving good satisfaction. The 
following tables give data in 
regard to the size of the vari- 
ous radiators, where Fi refers 
to height to center of steam 
supply, or supply and return 
tapping for water, while F2 re- 
fers to tapping for single pipe 
steam or return in two pipe 
steam. 

Pipe coil radiators or pipe coils 

ery satisfactor}\ They are made by joining pipes together 



Pressed Steel Radiator. 



RADIATORS, VALVES AND HEAT TRANSMISSION 83 




ffVYWVC 



MJWvaIj^ 



MEASUREMENTS OF AMERICAN RADIATORS 















1 




Heating 


Pattern. 


A 


B 


C 


L» 


E 


1 Fx 


Fi 


surface 
sq.ft. 


Rococo, Peerless one column . 


38 


31A 


4l 


si 


2I 


4l 


4 


3 




32 


25H 


4^ 


Si 


2| 


4l 


4 


2| 




26 


iqM 


4l 


Si 


2| 


4l 


4 


2 




23 


16^ 


4^ 


5l 


2| 


4l 


4 


If 




20 


I3fi 


4* 


Si 


2| 


4l 


4 


l| 


Two-column(PeerlessHospita] 


45 


38|f 


7I 


81 


2| 


4l 


4 


5 


radiators same as this, ex- 


38 


31A 


7f 


8| 


2* 


4l 


4 


4 


cept £ is 3 ins. in place of 


32 


25M 


7f 


81 


2| 


4l 


4 


3l 


2|) 


26 


19M 


7l 


81 


2| 


4l 


4 


2I 




23 


163^ 


1 


81 


2| 


4l 


4 


2| 




20 


i3ii 


78 


81 


2| 


4l 


4 


2 


Peerless only 


IS 
45 




7f 

^ 8 


8* 


2I 


4l 
4l 


4 


l| 


Three column 


38M 


10 


•^ 2 
2I 


4 


6 




38 


31A 


<u 


10 


2| 


4l 


4 


5 




32 


25M 




10 


2I 


4l 


4 


4l 




26 


19M 


10 


2.i 


4l 


4 


3! 




22 


153^ 


ID 


2| 


4l 


4 


3 




18 


113^ 


'S^-^c^ 


10 


2| 


4l 


4 


- i 


Four column 


45 
38 


38f^ 
31^ 


loh 


III- 


3 

3 


4l 
4I 


4l 
4l 


10 




lol 


X 0- 4 

Ili 


8 




32 


25if 


io| 


Hi 


3 


4l 


4l 


61 




26 


19M 


lol 


Hi 


3 


4l 


4l 


S 




22 


15^ 


loi 


Hi 


3 


4l 


4l 


4 




18 


iii^ 


loi 


Hi 


3 


4l 


4l 


3 


Rococo window 


20 


153^ 


I2§ 


I2| 


3 


3 


3 


5 




16 


iiA 


I2i 


I2I 


3 


3 


3 


3l 




13 


8^ 


I2i 


I2I 


3 


3 


3 


3 


Italian flue 


38 


31A 


8i 


81 


3 


4l 


4 


7 




32 


25T6 


sh 


81 


3 


4l 


4 


5l 




26 


19^ 


8i 


81 


3 


4l 


4 


4l 




20 


131^ 


8^ 


81 


3 


4l 


4 


3i 


Italian flue Dir.-ind 


39I 
33h 


31T6 

2Sl^ 


8i 


8^ 


3 
3 


6 


Si 
5l 


►, 




*-'2 

SI 


U2 

81 


6 


/ 
Si 




21\ 


19^ 


81 


81 


3 


6 


5l 


4l 




2X\ 


13^ 


8A 


8| 


3 


6 


5l 


04 



84 



ELEMENTS OF HEATING AND VENTILATION 



by retiim bends, Fig. 59, or by branch tees or manifolds, Fig. 60. 
In all cases, it must be remembered that some of the pipes are 







D 



Fig. 59.— Pipe Coil with Return Bends. 



U 



P 




P 



P 



Fig. 60. — Pipe Coil with Manifolds. 



Fig. 61. — Improper Form of Pipe Coil. 



apt to heat first, so that such a construction as shown in Fig. 
61 is improper, as the expansion of the top pipe before the other 
pipes are heated is apt to cause the rupture of the branch tees 



RADIATORS, VALVES AND HEAT TRANSMISSION 



85 



The arrangement shown in Figs. 59 and 60 permits the expan- 
sion of any individual pipe without straining the system. In 
all coil construction one must remember that any one pipe 



A 



^ 



Fig, 62. — Coil with Bends and ^lanifold. 



may expand more than any other. Fig. 62 is a fairly good con- 
struction, although here there may be unequal expansion of one 
pipe of any set which ^dll bring a strain on the return bend. 




Fig. 63. — Corner Coil. 



The fact that air may collect in any set is another objection 
to this system. Fig. 63 is a coil of good construction to be 
used at the corner of a room. In this form expansion may 
occur in any pipe. 



86 



ELEMENTS OF HEATING AND VENTILATION 



For the purpose of giving data to be used for coil construc- 
tion, the following table of certain sizes is added. 



DATA FRO:\I WROUGHT IRON PIPE 






Internal 
Area. 



sq.m. 



sq.ft. 



External 
Area. 



sq.ft. 



1 






;-i 


















cS - 




1 


ft 

It 


o 






1 
i 


c5.- 




H 




£ ° 

CI5 


u 


i 


c 



10 10. 
12 12. 



02 10 
00 12 



104 o. 
3040, 

533 0. 
86i!o. 
50 jo. 
036 0. 
356 0. 



0007 
0021 
0037 
0060 
0104 
0141 
0233 
0332 
0513 
0884 
1388 
2006 
3474 
5474 



0. 

o. 

0. 

I . 

2 . 
2. 

4- 
6. 
9. 
15- 
24. 
34- 
58. 
90. 



■54,12: 



229 
554 
866 
358 o 
164 o 
835 
430 o 
492 o 
621 o 

904JO 

301:0 

47 o 

43 ,0 

76 

68 



0016 
.0038 
0060 
0094 
0150 
0197 
0308 
0451 
0668 
1104 
1688 
2394 
4057 
6303 



095 
163 
216 o 

2740 

361 o 
443 o 
541 o 
646 
744 o 
05 I 
32 I 
59 I 
09 2 
62 2 
14 3 



.14; 0.421 

.22| O.84I 



28 

34 

43 

50 

62 

75 

92 

18 10.66 o 

45 1450 o 

73 18.76 o 

25 28. 18 o 

81 40.06 

33 49-00 o 



1. 12 . 

1 .67 
2.24 o 

2.68 
3-6i o 
5.74 

54 o 



.006 

. 010 

.014 

.023 

.03 

.05 

.09 

.14 

. 2 

■34 

•54 

.78 



18 
14 
14 

Hi 

irj 
115 

Hi 



29 
0.39 
0.40 
0.51 
0.54 
0.55 
0.58 
0.89 
0.95 
I. OS 
1. 16 
r.26 
1 .46 
1.68 
1.88 



,o.osi 
o.o8i 

O.Ili 

o. 16^ 

'o. 22^ 
0.27 
0.36 
O.57I 
0.755 
1.08 
1-45 
r.88 
I2.82 
3.20 
4-50 



For indirect heating the radiators are so arranged that the 
air passing the surface may abstract heat readily. The coil 
form of radiator or heater is arranged usually with four staggered 
rows of i-in. pipe. The pipes, Fig. 64, are attached at two 
places to a cast-iron base. In some forms, as those of the B. F. 
Sturtevant Co. and the Buffalo Forge Co., the division between 
the supply and return is made at the center of the base, while 
the Massachusetts Fan Company divides its base by a longi- 
tudinal partition. 

The pipes of Fig. 64 are constructed with one piece of each 
section with right and left ends. The steam is supplied through 
the upper section of the base and is discharged into the lower 
section. The small hole reheves the upper part of water. The 
figure shows the forms of base used by the two companies. 

The type shown in Fig. 65 is that used generally by the 
Massachusetts Fan Company, although it is also used by others. 
The base is divided by a vertical partition with a drain hole 




BUFFALO BASE 





o 



mrr, 



STURTEVANT BASE 

Fig. 64. — Coil Heater Section 

B. 



Fig. 65. — Massachusetts Coil. 



87 



88 



ELEMENTS OF HEATING AND VENTILATION 



at one point. The sections are of varying length for simpKcity 
in construction. 

Fig. 66 gives the form of the "positivflo" heater of the Green 
Fuel Economizer Co. In this heater the horizontal tubes are 



/'"i . A-ig'i-.g'i A 1^ .m.ja.sn.ja.jn.jn.m.jn.MLjn. 



mumiixinjuuujmi^UUXyjJ 



a 



rffWmfWfWfW^WWWrn 



o 



V tn" S" H W 'nJ I nr tif tri "g 5" S '3 W 'aj' S S '3 S H S H ^ © H 'm' I 'id 'ig 




attached at each end to a header box, the front one of which 
is separated into two parts by a partition, so that the steam 
flows in one direction through one half of the tubes, returning 
to the front by the other half. 

Cast forms of indirect radiators have been used for many 



RADIATORS, VALVES AXD HEAT TRANSMISSION 



89 



^S 



II 

m 



a 



years; the advantage claimed for them is a small number of 
joints and, if properly designed, a more compact radiator. A 
recent form introduced by the American Radiator Company 
is the Vento Cast Iron Hot Blast Heater, Fig. 67. In the figure 

a section through the pro- 
jections of the heater is 
shown from which it is seen 
that there is ample space 
for steam or water to reach 
all parts of the section. 
Occasional ties are cast in 
the interior to support the 
fiat plate. These sections 
are united by right and 
left hexagonal nipples which 




Fig. 67. — Vento Heater. 



Fig. 68. — Right and Left Nipples. 



are screwed in when the heaters are made up into stacks. 
The number of sections in a stack varies with the require- 
ments of an installation. Twenty-four is the largest number 
that is recommended to be put together, and when supply and 
return are to be placed at the same end of a stack eighteen 
sections is the limit. 

These are made of two forms, regular and narrow, in three 
dengths, 40 ins., containing 10.75 sq.ft. (reg.) or 7.5 sq.ft. (narrow), 



90 



ELEMENTS OF HEATING AND VENTILATION 



50 ins. containing 13.5 sq.ft. (reg.) or 9.5 sq.ft. (narrow), and 
60 ins. containing 16 sq.ft. (reg.) or 11 sq.ft. (narrow). 

The nipples are made of such length that the sections may be 
placed 4f, 5 or 5! ins. on centers. These give the following 
areas between sections for the passage of air. 



NET AIR SPACE 


IN SQUARE FEET 






Centers 


Sections 


4f in. 


5 in. 


of in. 


40 
60 


0.52 
0.65 
0.78 


0.62 
0.77 
0.92 


0.72 
0.91 
1.08 



The widths of the regular sections are 9 J ins. while the narrow 
sections are 6f ins. 

Fig. 69 gives the dimensions of the vento sections. Fig. 




56^1 ^ 

Fig. 69. — Measurements of Regular Vento Heaters. 



70 illustrates an Excelsior Indirect Radiator built by the Ameri- 
can Radiator Co. The detail of the end shows how the flow 
is directed through the upper pipe and down to the bottom pipe 
to the next radiator. The fins on the outside increase the heat- 
ing surface. These radiators are usually employed where 
individual heat stacks are placed beneath a room or set of rooms 
to be heated. 

The sections are 23! ins. or 36 by 8 ins. and the thickness 
or width is 3I ins. These contain 8 or 12 sq.ft. of radiating 



RADIATORS, VALVES AND HEAT TRANSMISSION 91 




W 



W 




Fig. 70. — Excelsior Indirect Radiator. 




Fig. 71. — Sterling Indirect Radiator. 



92 ELEMENTS OF HEATING AND VENTILATION 

surface. Fig. 71 represents their Sterling Indirect Radiator, 
which is somewhat similar in form. Each section contains 

20 sq.ft. of surface and requires a space of 36I by 15! by 3 J ins. 
The Perfection Pin Indirect Radiator, Fig. 72, may be used 

for the same purpose. The American Radiator Company 
build these in different forms, containing 10 sq.ft. and 15 sq.ft. 
of heating surface. The length is 36J ins. and the height is 
7I or II J ins. on the square part, while the projecting points 
increase the height 2J ins. The width of the sections is about 

2 1 ins. The tappings for this radiator are made at different 
points on the projecting ends to suit given conditions. 



o 



oWo°oOo2o9oWo°oOo°o°^^^^ 



,0 



Fig. 72. — Perfection Pin Radiator. 



All of the last forms are intended for small individual stacks 
with natural circulation. 

The coil radiators are sometimes formed as miter coils, 
Fig. 73, in which steam is admitted at the upper end and the con- 
densed steam is discharged at the lower end. The arrangement 
permits expansion to occur. 

Valves. The valves used on radiators are usually of the angle 
form and made with a union on one side, although any form 
of valve could be used. The reason for this pecuKar form is 
that it is desirable to have close connections from the radiator, 
as it is objectionable to have the pipes extend far beyond the 
radiator, obstructing space and forming a barrier over which 
persons might trip. 

The Norwall Packless Radiator valve, Fig. 74, illustrates 
the form of angle valve with the union on the left-hand side. 



RADIATOES, VALVES AND HEAT TRANSMISSION 93 

In the valve shown the valve disc has a piston A which 
prevents steam from coming in contact with the spindle. In 
addition there is a packing around the spindle at C held tight 




Fig. 73.— Miter Coil. 



by the spring D. The spring disc at B is intended to make up 
for the contraction of the spindle as the valve cools off, thus 
keeping the disc against its seat. The arrangement of threads, 
makes this a quick opening valve. 



94 



ELEMENTS OF HEATING AND VENTILATION 



The ordinary form of radiator valve as made by Jenkins 
Bros, or Crane is similar to this, with the exception that the 
spindle is attached by a shoulder to the disc. The spindle 
thread works in the bonnet of the valve and the stem is packed 
by a stuihng box. 

The American Radiator Company has adapted their cor- 




FiG. 74. — Norwall Packless Valve. 



rugated metallic bellows or Sylphon to the construction of the 
Sylphon Packless Radiator Valve, Fig. 75. In this valve the 
bellows A is attached to a cup B on the valve disc and to the 
bonnet at the top. This encloses the spindle in a space which 
is free from steam. The extension or contraction of the bellows 
occurs as the valve is moved in or out. The sylphon is made 
of steam brass and will stand repeated extensions without 
rupture. 



RADIATORS, VALVES AND HEAT TRANSMISSION 95 

The Q. O. Water Radiator Valve (quick opening) is shown in 
Fig. 76. Most water radiator valves are made in the form of 
cocks, so that a quarter turn will open them. The valve shown 
is so made that the conical body comes in contact with the 
body of the valve at top, bottom and small vertical strips on 
each side, which form a partition between the outlet and inlet 




Fig. 75. — Sylphon Packless 
Valve. 



Fig. 76.— Q. O. Water 
Radiator Valve. 



sides of the valve. The taper permits of taking up wear, the 
spring at the top pressing the valve against its seat. This 
spring presses against the washer around the spindle of the 
valve. 

In some cases a small hole is made in the valve allowing 
sufficient circulation in radiators which are shut off, to prevent 
freezing in cold weather. 



96 



ELEMENTS OF HEATING AND VENTILATION 



A comer valve, Fig. 77, of either right or left-hand con- 
struction is necessary at times on account of the position of the 
piping. This does away with elbows and shortens up connec- 
tions. 

. When it is necessary to turn steam or water on a radiator 
and have the same beyond the control of the occupants of the 
room, a lock and shield radiator valve, Fig. 78, is used. 
The spindle of the valve is surrounded by a shield, and a key 



( ) 





Fig. 77. — Corner Valve. 



Fig. 78. — Lock and Shield Valve. 



or extension handle fitting over the spindle is used to operate 
the valve. 

Special valves are used on radiators to cut down excessive 
use of steam and to reduce the pressure in the return pipes. 
Figs. 79 and 80 illustrate the Thennograde System of valves for 
this purpose. There are two valves used, the modulation or 
control valve A and the auto- valve B. The control valve A has a 
handle C with a pointer moving over a graduated scale, and 
on the handle is an adjustable pin D, moving over a cam E, so 
that when the pointer is at J the valve F is raised from its 
seat an amount which will just admit enough steam to heat 
J of the radiator. When the handle is moved to '' full " the rapid 



RADIATORS, VALVES AND HEAT TRANSMISSION 97 
rise in the cam opens the valve a large amount. The pin G 




is used to adjust the cam which is attached on one part of its 
circumference, the remaining part being split. 



98 



ELEMENTS OF HEATING AND VENTILATION 



The auto-valve is in reality a trap which will not allow 
steam to pass. It consists of a brass vessel H with a copper 
bottom which contains a liquid hydrocarbon such as gasoline. 
When this is cold the spring pressure lifts the valve, pressing 
in the copper bottom, which may be corrugated. The screw 

/ adjusts the position of this 



[f^Tr%n^%Ar%f^ 




Fig. 8o. — Thermograde Valves. 



SO that / is lifted from 
its seat when this condition 
occurs, but when steam 
reaches the discharge, the 
heat volatilizes part of the 
liquid in H and produces 
sufficient pressure to push 
the valve stem down against 
the spring pressure closing 
off the valve. / may be 
adjusted so that this occurs 
at some definite tempera- 
ture. 

The two valves are shown 
in their position on a radiator 
in Fig. 80. In this installa- 
tion hot- water radiators are used, as it is desired to have the 
steam supply the tops of all coils and blow out the air contained. 
There is no necessity for air valves in such a system as this, 
and with proper adjustment of the modulation valve the admis- 
sion of steam will heat about the amount of surface marked 
on the dial. 

Fig. 81 illustrates the method used by Warren Webster & Co. 
to accomplish the same result. 

The modulation valve A consists of a valve casing in which 
a disc D having four holes in it passes beneath a diaphragm E 
having one hole. The disc is moved by the handle F on 
the spindle. When the pointer on the handle is over the mark 
''i" on the dial a small hole in the disc registers with the hole in 
the diaphragm This admits enough heat to warm part of the 
radiator surface. When the handle is placed at the other 



RADIATORS, VALVES AND HEAT TRANSMISSION 99 

marks, "2," " 3 " or '* open," holes of the correct size come 
into the proper positions to admit more steam. 

The motor discharge valve is placed on the return end of the 




radiator. Water collecting will cause the ball float G to rise. 
This float acts as a valve and the water escapes over the com- 
position seat E. When the ball is seated air may be drawn 
from the radiator through the space between the tube in the ball 



100 



ELEMENTS OF HEATING AND VENTILATION 



G and the threaded rod. As soon as steam begins to go over,, 
this condenses in the threads and the passage of this condensate 
over the threads is very slow. 

The Monash valve to be placed on the drip of the radiator 
is somewhat similar in action to the above valve. 

As shown in Fig. 82 there is a water seal in this valve^ and 
yet the air can be drawn around the center spindle by the 




Fig. 82. — Monash Radifier. 



vacuum pump. There are by-passes to drain and clean the vaive. 
This valve is called a radifier. The advantage of these three 
return valves is that there is no pressure in the return pipe. 

The fact that air may collect in most radiators, preventing 
the proper heating of the radiator and producing noise, makes 
it necessary to use air valves on many forms of radiators. These 
may be automatic or hand controlled. In most cases there is 
considerable trouble with the automatic form, as they are liable 
to get out of adjustment. Fig. 83 illustrates two forms of 



iiADIATORS, VALVES AND HEAT TRANSMISSION 101 

compression air valves, one operated by a removable key, the 

other by a handle. These are nothing but small conical valves. 

In Fig. 84, an expansion form of automatic air valve is shown. 




Fig. 83. — Compression Air Valves. 

In this valve the core or cyhnder has a coefficient of expansion so 
different from that of the body of the v?ive that when adjusted 
by the slot in its end so that air will just discharge when cold^ 




Fig. 84. — Expansion Air Valve. 

the valve will be shut off as soon as hot water or steam strikes 
the valve. This form has been used for a considerable time. 

The Allen Automatic Air Valve, Fig. 85, is formed of two 
chambers, C and B, connected by a hole A at the bottom. 



102 ELEMENTS OF HEATING AND VENTILATION 

The cylinder D is closed. When there is no water in C the 
cylinder D rests on the bottom of C and the pin at its upper end 
does not fill the hole. Air will then escape from the radiator 
which is connected at E. When steam reaches the valve, the 
condensation of it fills the bottom and floats the cylinder D, 





mm^mmm} ^^ 



Allen Air Valve. Libra Automatic Air Valve. 

Fig. 85.— Air Valves. 

closing the hole. After this cools off the contraction of the air 
in B draws some of the water from C and allows D to fall, thus 
opening the air vent. The valve is kept hot by conduction 
from the radiator as long as the steam is turned on. 

The valve shown in Fig. 85 is the Libra Automatic Air Valve. 
The inner cylinder is open at the bottom and when steam enters 
the valve, the air contained within the cylinder, expanding 



RADIATORS, VALVES AND HEAT TRANSMISSION 103 



from the heat, forces the water out and floats the cylinder, 
closing the valve. This water collects when the valve is first 
attached to the radiator. 

The above valves permit air to enter the radiator after steam 
is shut off. This of course means that when the radiator is 
opened again, a certain time must elapse before the air is all 
removed and the radiator is completely heated. To prevent 
this action the Norwall Automatic Syphon Air and Vacuixm Valve 
is used. This valve is similar 
to those described above with 
the addition of a syphon A and 
the vacuum head B. The S3^hon 
A extends into the radiator and 
fills the lower part of the valve 
with water, if the radiator has 
liquid in it, before this reaches 
the level of the outlet. This 
water lifts the float and closes 
off the discharge until the water 
is drawn from the radiator. 
The vacuum head B contains a 
diaphragm of bronze containing 
a port which may be closed by 
a ball on the end of a small rod. 
The rod is supported by a yoke 
and two adjusting nuts. The 
length of the rod is such that 
when the pressure below the dia- 
phragm is slightly above atmospheric pressure the disc is 
raised, allowing air or vapor to pass out through holes in the head. 
As soon as the pressure is atmospheric the diaphragm rests on 
the ball, closing off the opening around the rod. The greater 
the vacuum below the diaphragm, the tighter the opening is 
closed. 

The sylphon bellows is applied to an air valve in Fig. 87^. 
The bellows has a volatile liquid within it which vaporizes when 
subject to heat from steam and closes the air valve. The float 




Fig. 86.- 



Combined Air and Vacuum 
Valve. 



104 



ELEMENTS OF HEATING AND VENTILATION 



above is intended to close the vent if the radiator is flooded with 
water. The vent pin is self-guiding. 

The Sylphon Vacuum and Air Valve. Fig. 87J5 has the closed 
bellows with the volatile liquid at the bottom and a float D, 
while above this, carrying the valve seat, is an empty bellows 
so made that the valve seat rests against the valve. When 
pressure from the radiator is slightly in excess of the atmos- 
phere, the bellows moves upward from the pressure and the 
valve opens so that air can escape, the valve closing by the lower 
bellows or float as soon as this is heated by steam or lifted by 




JZX 




A, Sylphon Air Valve. B, Sylphon Air and Vacuum Valve. 

Fig, 87. — Sylphon Air Valves. 

water. When a vacuum is formed in the radiator the valve is 
held closed by the excess of pressure on the outer part of the 
upper bellows. 

For venting the whole system at the end of a return line 
the Sylphon Vent Valve, Fig. 88, is used. In this the inner 
sylphon is closed and filled with a fluid which operates to close 
the upper valve by pushing it upward against the seat and the 
outer sylphon operates to close the vent as soon as the pressure 
in the pipe Hne becomes equal or less than atmospheric pressure. 
The cylinder within the lower sylphon is to keep this from 
closing too much when cold. 



RADIATORS, VALVES AND HEAT TRANSMISSION 105 

Heat Transmission through Radiators. Radiators trans- 
mit heat by conduction to the outer surface of the wall; from this 
point it is transmitted by radiation to objects around and by 
convection to the air. The radiant energy emanates in all 
directions, and hence for the ordinary radiator the large part of 
the surface cannot radiate heat to the outside objects, as this heat 




Fig. 



-Sylphon Air Vent Valve. 



is intercepted by the other sections of the radiator. Newton was 
one of the first to state a law for radiant energy, and he was 
followed by Dulong and Petit, Rosetti, Stefan, Weber, Bottomley, 
Paschen and Petavel, extending from 1 690-1 898. Most of 
these give radiation in the form H = K{Ti^ — T2^) where K is 
the constant of radiation and Ti and T2 are the absolute temper- 
atures of the hot body and the surrounding cold bodies respect- 



106 ELEMENTS OF HEATING AND VENTILATION 

ively. The values of a vary according to the different investi- 
gations, 

a = i, Newton; 

a = 3, Rosetti; 

a = 4, Stefan; 

a = 5.7, Bottomley, Paschen; 

a = 5, Petavel. 

According to Dulong and Petit the expression is 

H = KC'', 
and to Weber, 

H = KTC''. 

Stefan from experimental data, and Boltzmann from 
thermodynamic reasoning independently determined that the 
energy radiated from a black body is proportional to the fourth 
power of the absolute temperature, or 

E = K{T^-To^); 

£ = radiated energy per square foot per hour; 
K = Si constant; 

r = absolute temperature of radiating body; 

To = absolute temperature of receiving body. 

In English measures K = (i6Xio~^^). 

This is known as the Stefan-Boltzman radiation law, and 
refers truly to a black body; but since the heat reflected and 
radiated from a body is equal (by the Stewart-Kirchhoff law) to 
that emitted from a black body, this rule may be applied if 
necessary to any body. It represents the best law of radiation. 

Carpenter states that the larger part of the heat transmitted 
from a radiator is due to convection, and this is reasonable as 
pointed out before on account of interference. From experi- 
ments of Ser and others as mentioned by Dalby in London 
Engineering, Oct. 22, 19 10, and from the discussion of this 
paper by Nicholson, as well as by his experiments and those 
performed by the makers of indirect heaters, it is evident that 



EADIATORS, VALVES AND HEAT TRANSMISSION 107 

the amount of heat removed from a radiator depends on the 
velocity of the air passing it. 

The air seems to wipe the heat from the surface. There is 
apparently a fihn of air in contact with the heating surface 
which prevents the transmission of heat, as its conductivity is 
low, and so long as it remains in contact with the surface it cuts 
down the temperature difference between the air to be warmed 
and the conducting substance, which in this case is the air film. 
By causing the air to pass rapidly over the metal surface or to 
impinge on it, the thickness of the film is decreased, the true 
temperature difference increased, and the amount of heat 
transference is thus increased. 

The data seem to show that the heat transference at any 
place is given by the forms : 



or 



H=fV.(ts-ta)A (51) 

H = {B+Cgv){ts-ta)A ........... (52) 

z; = velocity in feet per second; 

ts = temperature of steam or hot water in deg. F. ; 

4 = temperature of air in deg. F.;^ 
A =area in square feet; 
f, C, B, constants; 

p= density. 

For a given velocity v, the quantity of heat given off by the 
area dA, is 

dH = Ki(ts-t)dA, (53) 

where Ki is a constant, although by some it is considered to 
depend on t. 

The quantity t will vary between the two limits h and t2 
as the area varies between o and A. 

H = Ki(mesinAt)A (54) 



108 ELEMENTS OF HEATING AND VENTILATION 

Now 

dH = Mcj,dt; 

M =mass of air heated per hour; 

Cp = specific heat of air ; 

H =Mcp(t2-ti) 

(Variation in Cp not appreciable over this range.) 



Hence 



^2 = temperature of air leaving radiator; 
ti = temperature of air entering radiator. 

Mcpdt = Ki{ts-t)dA (55) 

dt 
Mcp—- = KidA 

Is f 



Mc,\og!-^=K,A (56) 

h~t2 



Now 



Hence 



TT 

Mcp= — - 
t-i — h 



and substituting in (54) 

to — ti 



or 






E = K,^^A (58) 



RADIATORS, VALVES AND HEAT TRANSMISSION 109 
If the term involving velocity is introduced this becomes 

H^KWv-'^A* (59) 

Now in general the formula used for heat transmission is 

E = K{ts-tr)A (60) 

where //= temperature of the room or the mean temperature 
of the air in an indirect heater. Comparing this with (54) it 
is seen that K must be of the form 

^=^^^'^S:,-i^ (^^) 

It is seen that K will vary with v, ts, t-z, h and U. In case of 
direct radiation tr = ti, while in indirect radiation 

. J2±h 
tr — 



* If the transmission depends on a power of the temperature difiference the 
following results: 

dH = _' (ts — t)dA = Mcpdt. 





KidA=Mcp 


[ts-tT-Ht. 






n 


{ts-hY-its- 


-h) 


Now 


H=Mcp{h-h). 




Hence 


K,An{h-h) 
{ts-hY-{ts-hr 




Now 


H ^' 


ni^i)A, 




(aO 





,.] 



This holds for all valus of n except for » = 0. This was the value used above. 



110 ELEMENTS OF HEATING AND VENTILATION 

Because of the complication of this formula, experimental 
determination of the quantity K is made without finding Ki 
and computing K. 

. In performing the experiment the radiator is supphed with 
steam, the quahty and pressure of which are determined by 
instruments, and the temperature and weight of the condensate 
is found. From the data H is given by 

H = M{q+xr-qo) =M{i-qo), 
where 

if = weight of steam condensed per hour; 
^* = heat content of entering steam; 
^o = heat content of leaving steam. 

Knowing Ai, ts and ta, the quantity K may be found. 

In direct radiators the velocity v is about the same in radiators 
of the same type, and so there will not be much difference in K 
for different conditions. But on account of the height and posi- 
tion of the radiating surface causing a difference in this quantity 
a change is expected in the value of K for differing radiators. 
The kind of surface would affect K, so that wrought iron, cast 
iron, painted radiators and bronzed radiators are all expected 
to give varying values of K. 

The effect of radiation is present principally on the edges of 
the center sections and from the faces of the end sections, 
and as a result of this the value of K is greater for radiators 
of a few sections or coils than for those having a number of 
sections. The formula shows clearly that ts, t2, h and 4 affect 
K, and so in reality there should be a variation in this quantity 
for different steam, water and air conditions. 

Carpenter quotes tests giving K from 1.23 to 1.97, while 
Rietschel gives values in his tables as low as 0.51 and as high 
as 2.65 with steam in a single pipe. 

With a single section Denton and Jacobus found a constant 
as high as 2.39, while with a series of sections the value 1.97 was 
obtained. In another case 2.24 for a single section was reduced 
to 1.30 when 9 were used. 



RADIATORS, VALVES AND HEAT TRANSMISSION 111 

The condition of the surface of the radiator effects the amount 
of transmission. Experiments have been made by Carpenter 
and by Allen, and these seem to show that bright paints 
would decrease the efficiency of transmission while dark paints 
or even white lead increased the efficiency. In regard to bronz- 
ing, their results differed: Carpenter found an increase while 
Allen reports a decrease in efficiency. The number of coats of 
paint did not seem to effect this result, the outer coat being the 
determining factor. 

The results of experiments show that the radiator of large 
surface, long or high, will give a smaller rate of transmission, 
K, than a small radiator. 

Considering all results it will be well to take A' as 1.75 * 

Then £'=1.75(222 — 70) = 265 for low pressure steam; 

_ /170+150 \ . , 

£^ = 1.751 ~7o ) = 160 for hot water. 

In the case of low pressure steam the pressure is assumed 
to be 3 lbs. gage, and for the hot water, the water is supposed 
to enter at 170° F. and leave at 150° F. 

With indirect heaters the effect varies with the velocity. 
The usual method is to use the formula, 

According to Carpenter, 

i^=2+i.3Vz); 

V = average velocity over coils in feet per second ; 
4 = steam temperature; 
/i = inlet temperature; 
to = outlet temperature. 

* Rietschel gives the following values of K, according to Kinealy: gas to air 
through clay plate 1.09, gas to air through cast or sheet iron 1.4 to 2.0, gas to 
water or reverse through cast or sheet iron 2.6 to 4.0, steam to air through 
cast or wrought iron 2.2 to 3.6, steam to water through metal 166 to 200. 



112 



ELEMENTS OF HEATING AND VENTILATION 













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SUQUOOS 

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KADIATOES, VALVES AND HEAT TEAXSMISSION 113 



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114 



ELEMENTS OF HEATING AND VENTILATION 



240 
220 
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100 200 300 400 500 600 TOO 800 900 1000 1100 1200 1300 1400 
Velocity in Feet per ]\Iia. 

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'0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1800 1400 
Velocity in Feet per Mia. 

(b) Air Entering at 20" F. 

Fig. 91. — Outlet Temperature from Buffalo Forge Heaters of Four Coils to the 

Section with Steam at 5 lbs. Gage Pressure. 



RADIATORS, VALVES AND HEAT TRANSMISSION 115 




100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 
Velocity in Feet per.Min, 

(c) Entering Air at 40° F. 

Fig. 91.— Outlet Temperature from Buffalo Forge Heaters of Four Coils to the 
Section with Steam at 5 lbs. Gage Pressure. 



1000 
900 
800 
700 
600 




























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100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 14i00 
Velocity in Et.per Min. 

(a) Entering Air at 0° F. 

Fig. 92. — Heat Transmitted per Lineal Foot of i Inch Pipe at Different Velocities 
with Various Sections of 4 rows of Pipe each, Steam being at 5 lbs. Gage 
pressure and Entering Air at 0° F., 20° F. and 40° F. Velocity at 70° F. 
(Curyes constructed from data published by Buffalo Forge Co.) 



116 



ELEMENTS OF HEATING AND VENTILATION 



AOOO 




IJOO 300 300 400 500" 600 TOO 800 900 IQOO 1100 1200 1300 1400 
Velocity in Ft. per Min. 

(b) Entering Air at 20° F. 



1000 
900 
800 
700 
600 



3 500 



100 200 300 400 



500 600 TOO 800 900 
Velocity in Ft. per Min. 

(c) Entering Air at 40° F. 



1000 1100 1200 1300 1400 



Fig. 92. — Heat Transmitted per Lineal Foot of i Inch Pipe at Different Velocities 
with Various Sections of 4 rows of Pipe each, Steam being at 5 lbs. Gage 
pressure and Entering Air at 0° F., 20° F., and 40° F. Velocity at 70° F. 
(Curves constructed from data published by Buffalo Forge Co.) 



RADIATORS, VALVES AND HEAT TRANSMISSION 117 

The Buffalo Forge Company give tables to be used with their 
heating coils of pipe, and the American Radiator Company 
give results of tests with their vento heater sections. These 
curves give the temperature increase for different velocities. 
These have been plotted as curves shown in Figs. 89, 90, 
91, 92, which may be used for computing areas required for 
indirect radiators. These curves and the formula of Carpenter 
give for values of K the following : 



Velocity 
in Ft. per M. 


Carpenter 


I Section of 
4 Coils. 


3 Sections of 
12 Coils. 


I Vento. 


3 Vento. 


600 


6.1 


7-1 


7-7 


71 


6.6 


800 


6.7 


9.6 


9.2 


8.3 


7-9 


1000 


7-3 


II .2 


10.7 


9-3 


9.0 


1200 


7.8 


12.4 


II. 8 


10.4 


10. 


1400 


8.3 


13.2 


12.5 


II .2 


10.8 


1600 


8.6 


13 -7 


13.0 


II. 8 


II-5 



These results indicate that a formula such as that of Carpenter 
does not hold as K is a function of the temperature drop 
along a set of surfaces, hence it is best to use a set of charts simi- 
lar to those given. 



CHAPTER V 
METHODS OF CALCULATING HEAT REQUIRED FOR ROOMS 

The methods used in practice for finding the heat loss in 
rooms varies according to. the engineer. In any case a system 





















No. 


Bdg RooM.__ Location 


Ceiling Ft. 


Wall 


KIND 


Thick 


Area 


AT 


c 


Ex. C. 


HEAT LOSS 


















































































































































































Ceil. 
















Floor 
















Sketch 
N 

W E 

S 


Occupants Nc 
air supply— 

T.CHAN 

Flues 


Total 

Ventilation 


CU.KT. 

GE HT 


Heating Surface | 


Kind 


Make 


Sq.ft. 


ST. 


D 
































VoLU^ 


flE 


__Xu. Ft 


1 













Fig. 93. — Data Sheet. 

of calculation should be used which will give results in a direct 
manner and one in which these may be readily checked. One 
method is to have ruled pages in a book with entries, as shown 
in Plates I, II. A certain part of the page is used for one room, 

118 



CALCULATING HEAT REQUIRED FOR ROOMS 



119 



and the data for the room is taken from plans and entered. 
Another form used by the late Prof. H. W. Spangler is shown 
in Fig. 93. To fill out sheets in either method the plans of the 
building to be heated are first studied and the rooms are given 
designating numbers, and beside the numbers the desired or 
assumed mean temperature of the room is marked. The points 




Fig. 94. — Cellar Plan. 

of the compass are marked and then the data required on the 
sheets are filled out. 

To illustrate the m^ethod of work the plans of a two-storied 
house, with the first story of brick and the second story of 
shingles, shown in Figs. 94 to 98, will be considered. 

The temperature of the attic will be taken as 26° F. and of 
the cellar as 36° F. The ceilings as shown by the section are 
not high, and no allowance must be added to the temperature 
at head level to allow for excessive height of story. 

The slanting roof is of shingles without sheathing or paper 
and the deck roof is sheathed with wodd on which is a metal 



120 



ELEMENTS OF HEATING AND VENTILATION 



<^ Oft 









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CALCULATING HEAT REQUIRED FOR ROOMS 



121 











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122 



ELEMENTS OF HEATING AND VENTILATION 



cover. The first floor is composed of ship lap over which build- 
ing paper is placed and on top of this is a layer of tongued and 
grooved flooring. There is no plaster below. The second 
floor is similar to this with plaster on the lower side of the joists, 
while the attic floor is composed of ship lap only with plaster 




Fig. 95. — First Floor Plan. 



below the joists. The values of K taken for these are 0.23 for 
the first floor and 0.22 for the attic floor or ceiling of the second 
floor, as the heated room is below, see page 65. The second 
floor is not considered as the temperature is the same on both 
sides; but had the second floor been 15° lower in temperature, 
the value of K used here for the ceiflng of the first floor and floor 
of the second story would have been 0.16. If the second story 



CALCULATING HEAT REQUIRED FOR ROOMS 



123 



were 15° higher in temperature than the first floor, then the 
value of K would have been 0.03, as the hot room would be 
above. 

The first floor walls are made of 8 ins. of brick work, a f in. 
air space and i in. of lath and plaster, hence, from page 64, 
the value oi K is 0.24. The second story is sheathed with ship 
lap on which shingles are placed over two layers of paper; the 




VsS'b" \ [ - i'^4Ys3^4" f pX fjn \ 3^8 'k 5 6" \ 



Fig. 96, — Second Floor Plan. 



value of K is therefore 0.20. The glass has a value of K of 0.96. 
The doors on the outside and the French windows are considered 
as having the same values as glass. 

The temperature of the attic could have been worked out 
^by the method given by Eq. (39), 

0.22(70-/0) =0.4(^0 — 0°). 

In the equation above the value of K for the roof is taken 



124 ELEMENTS OF HEATING AND VENTILATION 

as 0.4; ta is the temperature of the attic. In this case, the solu- 
tion of the equation gives 

With a thicker roof or one sheathed and with paper beneath 




Fig. 97. — Section. 

the shingles, the value of K would equal 0.3, and then the equation 
would give 

/a = 3o°F. 

The drawings of the building are now taken and the various 
rooms are marked with distinguishing numbers, and beneath 
these numbers the temperatures to be expected and the changes 
per hour if the ventilation is figured in this way. In numbering 
rooms in large buildings it is well to use combinations of numbers 
to designate floors. Thus all numbers beginning with 100, 



CALCULATING HEAT EEQUIRED FOR ROOMS 



125 



' as 105, 120, 132, etc., are found on the first floor, while 320^ 
318, 306 are found on the third floor. 

The table is now filled in, the number of the room, then a 
rough sketch of the same, showing the form of the room, then 




BIB ■ 




w 



a column for heights and volumes and then a column giving 
the occupants or the nimaber of changes per hour. The sketch 
is made with the north side to the top and the windows and 
doors designated by heavier lines. It is also well to mark. 
^ temperatures on the various sides of the room. 



126 ELEMENTS OF HEATING AND VENTILATION 

The losses for the various sides of the room are now filled out 
with the floor and ceiKng, giving the total area, glass or door 
area, net wall area, difference in temperature, value of the 
coefficient and finally the factor wHich is to care for exposure. 

For high rooms the effect of increased temperature required 
would be shown in a greater temperature difference. The 
fact that increased radiation might be needed for intermittent 
heating would be shown in column headed, " Remarks." 

By multiplying together the area, constant, temperature 
dift'erence and factor, the amount of heat required for each side 
is found and entered in the heat column. The sum of all heats 
excepting that for the ventilating air is placed in the total heat 
column, with the ventilating heat as a separate item. These 
various columns may be added together by floors giving totals 
which are used in making checks. 

In applying this method, although outside doors are taken 
as equal to windows, they in reality have a much lower constant, 
and for that reason on interior work or in any place not exposed 
to the wind, their true values, given in Chapter III, may be 
used. 

The application of the table described above will vary with 
various systems and will be considered in the succeeding chapters. 



CHAPTER VI 

DIRECT STEAM HEATING 

In direct steam heating the steam is carried to the radiators 
on the different floors in several ways. 

Fig, 99 illustrates the single pipe system. In this method 
of arranging piping, the steam flows from the boiler through 




Fig. 99. — Single Pipe System. 

the main and risers to the various radiators. After condensa- 
tion the water falls back through the radiators and rises into 
the main. The main is carried around the basement pitching 
in the direction of flow until it drops below the water line of 
the boiler. In this system the radiators are each provided 

127 



128 



ELEMENTS OF HEATING AND VENTILATION 



with an air valve on the opposite side from the inlet. The 
system is not as positive as the two-pipe system of Fig. loo, 
but the pipes are fewer in number. Although larger pipes are 
required, the cost is less than the two-pipe system. This system, 
unless very carefully installed, is a noisy one, owing to the water 
hammer. 

In the double-pipe system of Fig. loo separate steam risers 
and return risers are connected in the basement to the steam 
main and the return main respectively. 




;i«^t 



^^ 



-JH^Jti- 





Fig. ioo.- — Two-pipe System. 

The connections to the risers are made so that no pockets 
will form and each riser is controlled by a valve. 

This system has the advantage that the condensation is 
cared for by a separate Kne and does not travel in the same 
pipe as the steam. This double flow in the same pipe may 
cause hammering when the system is started. Air valves are 
required to reheve the air which may be held in the top of 
a radiator, as, after a very short time, the supply and return 
pipes are filled with steam. This is the objection to this system 



DIRECT STEAM HEATING 129 

with ordinary valves. The steam in the return pipe will feed 
a radiator even after the supply valve is closed unless the return 
valve is shut also. The pressure in the return pipe causes a 
sluggish circulation at times. To overcome this such valves as 
the auto valve of the Thermograde Co., the seal valve of Warren 
Webster & Co., the seal valve of the Monash Co., or a similar one 
is used on the return. In this way there is no pressure in the 
return and the circulation is positive. Warren Webster & Co. 
use a vacuum pump on their return pipe in their system, thus 
carrying so low a pressure that the steam in the supply pipe is 
practically at atmospheric pressure. This is of advantage when 
the exhaust from engines is used, as the back pressure on the engine 
is not great and there is little pitch to the return pipe. 
Unless a valve of the type of these return valves were used it 
would not be possible to keep the pressure at such a low point 
in the return. This system is known as the vacuum system. 

Another system of distributing the steam is that of the 
overhead distributing main or Mills' system, Fig. loi. In this 
the steam is carried through a riser A to the distributing main 
B in an attic or upper floor of a building. From this the risers 
C are taken off. The return risers D are carried downward and 
connect to the return main F. The condensation in the steam 
risers C is collected in the drip line E, although at times these 
drips are put into the return main or the condensation is cared 
for by the lowest radiator. These two latter methods are not 
good and that shown in Fig. loi should be used in caring for 
the drip. In such a case the drip line is connected to the return 
through a steam trap. 

For high buildings this system is often employed with the 
distributing main near the middle of the height of the building, 
steam being distributed up and down from that point. 

The same system is used with a single riser system at times, 
the riser being connected to the distributing main above and the 
return main below. The drip is ehminated in this case and 
so are the return risers. This is sometimes called the complete 
circuit system and the one pipe system. 

In many small steam installations the complete heating 



130 



ELEMENTS OF HEATING AND VENTILATION 



system is connected to a boiler without the use of a pump, as 
shown in Fig. 2, and in such a case the drip of Fig. loi is not 
necessary. The method just described, of a single riser system 
with an overhead distribution, is quite good, as the circulation 
is positive in the suppHes, especially if the return is sealed by 




Fig. ioi. — Mills Svstem. 



dropping the pipe below the water line by a vertical leg. In 
cases of central station heating, where returns from several 
buildings are delivered into a common return pipe, it is well to 
allow each building to discharge through a trap into the main 
return pipe. If this is not done one building may interfere 
with the proper heating of another. The return from one 



DIRECT STEAM HEATING 131 

building may prevent the air from being driven out of another 
one. 

To find the size of radiators required for any room, the heat 
found in Plates I or II is divided by the heat transmission per 
square foot of heating surface as found in Chapter IV. A 
simple number to remember for low pressure steam heating is 
250 B.t.u. per square foot per hour. Dividing the amount 
of heat in the case mentioned above by this, the amount of 
heating surface is found. 

To check the results of computation it is well to di\ide the 
cubic capacity of the various rooms by the square feet of radiation 
in them, obtaining the cubic feet of space heated by one square 
foot of heating surface. This quantity varies with different 
kinds of construction and amount of window space, but the num- 
bers serve to check any large errors after the designer has had 
experience. To guide the student the following table has been 
prepared from various sources: 

CUBIC FEET OF VOLUME PER SQUARE FOOT OF 
DIRECT RADIATION 

Residences : 

Li\ing rooms 35 to 60 

Sleeping rooms 50 to 80 

Offices 40 to 80 

Schools 40 to 80 

Factories 75 to 100 

Assembly halls 75 to 100 

Hotels 75 to 100 

Stores 75 to 100 

Churches 125 to 200 

Auditoriiuns 125 to 200 

Gymnasiums 100 

Work shops . 150 

From the table of Chapter IV, the numbers of sections of 
different forms of radiators required for these amounts of heating 
surface are found. The height of the radiator is fixed by the 



132 



ELEMENTS OF HEATING AND VENTILATION 



condition in the building, such as heights of window sihs, etc. 
The selections for the building computed in Chapter V are 
shown in the tables of that chapter. Radiators are usually 
placed in front of windows to cause a blanket of hot air in front 
of the window and to heat the leakage air. They should not 
extend above the sill. 

Some authorities prefer to put them on a wall near a window, 
but not in front of it, claiming that in this way there is no down 
current of cold air to interfere with the up current of hot air. 
The cold air drops from the window, passes to the radiator, and 
there is a strong rising current aiding in the heat transference. 
There are two objections against this: valuable wall space 
for furniture is taken, and there will be cold drafts from the 
window. 

The radiators being selected, the size of outlets should be 
fixed. These are standardized by the radiator companies and 
are given in the table below : 

TAPPING FOR RADIATORS 



Single Pipe. 


Two Pipe Steam. 


Hot Water. 


Sq.ft. Area. 


Tapping. 


Sq.ft. Area. 


Supply. 


Return. 


Sq.ft. Area. 


Supply. 


Return. 


24 


I in. 


48 


I 


3 

4 


40 


I 


I 


24-60 


li " 


48-96 


li 


I 


40-72 


li 


li 


60-100 


li " 


96 


li 


li 


72 


l| 


i| 


100 


2 













The connections from the radiator to the risers should be 
arranged so that as 'the riser expands and contracts, the radiator 
will not be Hfted from the floor. The best way to arrange 
these branches is shown in Fig. 102, an isometric drawing. The 
isometric method of representing piping is very useful. In 
this the vertical lines represent vertical pipes; horizontal Hnes, 
those parallel to the plane of the drawing; and lines at 30°, 
lines perpendicular to the plane of the paper. Single lines are 
used to represent the pipes, and these may be solid or dot and dash 
lines. Thus, Fig. 104, represents four ways of connecting radi- 



DIRECT STEAM HEATING 



133 




Fig. 1 02. — Branch Connection. 



Up 





J 



Fig. 103.— Isometric Directions. Fig. 104.— Radiator Connections. 



134 



ELEMENTS OF HEATING AND VENTILATION 



ators. The third method should never be used, as the expan- 
sion of the riser will lift the radiator and this tends to break the 
fittings at radiator if it does not actually break them. The second 
method is satisfactory if the branch is long enough to have 
some spring, and in the first or best method there is a chance 
for the branch to swivel on the ells and care for the expansion. 





LOOKING NORTH 



LOOKING EAST 








D 



3d" 



Js'ik' 



LOOKING SOUTH LOOKING WEST 

Fig. 105. — Development of House. 

Risers are usually arranged so that a number ot radiators 
come on the same line. This cuts down the number of risers 
and gives a cheaper job. To study the distribution properly 
and to give the heating contractor a knowledge of what is to be 
done it is well to make a small scale drawing, usually tV in. 
to the foot, showing the development of the walls of the building, 
with windows and partitions marked on it, and on this lay out 



DIRECT STEAM HEATING 



1.35 



the radiators and risers. These views are all from the inside 
of the building, showing the wall as seen from the room. Fig. 
105 shows such a development for the house figured in Chapter 
V. On this view the radiators are placed and each radiator 
and riser is given a designating mark. The radiators are marked 
with the number of the room followed by small letters a, b, c, 
d and e, if there are more than one. 

Thus in room 5 there are two radiators, 5a and 5^. The risers 
are marked A, B, C, D and E, or by some other method, as 
I, II, III, IV, etc. The radiators and risers are also marked 
on the plans. Care must be taken in placing these to see that 
there is no interference with the placing of the furniture. Where 
possible the heating engineer should consult with his chent 
about the placing of radiators. 

The risers are usually proportioned by the number of square 
feet of radiation on them, and the table below gives the size for 
various amounts of radiation as recommended by Carpenter 
and others. 

RISERS FOR VARIOUS HEIGHTS OF BUILDING 



Radiator 








Radiator 








Surfaces 


Low. 


Medium. 


High. 


Surfaces 


Low. 


Medium. 


High. 


in Sq. Ft. 








in Sq. Ft. 








20 


I 


IT 


i| 


400 


2 


A 


3 


60 


li 


li 


li 


500 


2h 


3 


3 


100 


li 


li 


li 


60c 


2\ 


3 


3i 


200 


I* 


2 


2 


700 


3 


3 


z\ 


300 


2 


2 


2 


800 


3 


3l 


4 



The risers should be controlled by valves, so that any radiator 
or branch may be fixed without shutting down the whole plant. 
The valves on the risers leading to a given radiator are closed 
when necessary for the repair of the radiator or connection. 
This can be quickly done and there is no interference with the 
radiators on other lines. 

Where risers and vertical pipes of branches pass through 
floors or where horizontal pipes pass through partitions, floor 
and ceiling plates, Fig. 106, are placed around the pipes to close 



136 ELEMENTS OF HEATING AND VENTILATION 



the end of the hole in the plaster and give a neat finish. These 
are sometimes attached to the ends of the sleeves which are 
used to surround pipes which pass floors and partitions. The 





Fig. io6. — Floor and Ceiling Plates. 



sleeves, Fig. 107, are made of cast iron or galvanized iron. 
They form an air space around the pipe and also ensure the pipe 
having a chance to expand and contract without breaking the 
plaster. By the use of an air space around the pipe the chance 






Fig. 107. — Floor Sleeve. 



Fig. 108. — Pipe Hangers. 



for charring timber construction, and the resulting danger of 
fire is removed. 

The risers are supported by pipe hangers, Fig. 108, attached 
to a top horizontal branch of the riser or by band anchors. Fig. 
109, attached around the vertical feeder. The anchor type is 
the better one to employ, as this permits one to support the riser 



DIRECT STEAM HEATING 



137 



O 



near the base or at the middle of its length. If at the middle 
the expansion occurs in each direction. If the end of a riser 
has any expansion the connection 
to the feed Hne or return must be 
made to allow for this. Of course, ^^^ 
it is possible for pipes to bend ^^:^ 
sufhciently to permit of expansion ^ 

if long enough, but there is danger 
of the fitting breaking, conse- 
quently it is well to arrange the 
connection from main to branch as 
in A, Fig. no. If the end of the 
pipe is anchored the connection 
may be made as at B, Fig. no. 

^, , . ^ J r> -n* EiG. lOQ. — Clamp or Anchor. 

The connections A and B, Pig. no. 

permit the main to move without danger of rupture, as the ver- 
tical elbows will allow the branch to swivel . At times 45^ 





Fig. 1 10. — Branch Connections. 



elbows are used to permit of expansion. Expansion in most 
heating systems can be cared for by swinging ells, and when 



138 



ELEMENTS OF HEATING AND VENTILATION 



possible this should be done or expansion bends or corrugated 
pipes should be used. The slip expansion joints cause consider- 
able trouble by leaking at the packing in the stuffing box. 

The expansion to be allowed for various steam pressures 
is different. The table below gives the amount to be cared for 
in inches for each loo ft. if the original pipe is at o°, 30°, 60°, 
70° when various steam pressures are used. 

EXPANSION IN INCHES 
Per 100 Feet 



Original 


Gage Steam Pressure. 


Water Temp. 


Temperature. 


















150 


100 


40 


10 


5 


212° 


180° 





2.84 


2.63 


2.23 


1.87 


1.77 


1-65 


1 .40 


30 


2.61 


2.40 


2 .00 


1.63 


1-54 


1. 41 


1. 17 


60 


2.38 


2.16 


1.76 


I .40 


I-3I 


1. 18 


0-93 


70 


2.30 


2.08 


1.69 


1.32 


1.23 


1 .10 


0.81 



The steam mains and return mains are designed in several 
ways. The first method is to use tables giving the amount of 
surface to be cared for by mains of various sizes. These tables 
are made for lines of a definite length, the usual length being 
100 ft. 

CAPACITY OF PIPES IN SQUARE FEET OF RADIATION FOR LENGTH 
OF 100 FEET, ACCORDING TO A. R. WOLF 



Diam. 


Radiation. 


Diam. 


Radiation. 












2 lbs. 


5 lbs. 




2 lbs. 


5 lbs. 


I 


36 


60 


4 


1920 


3200 


li 


72 


120 


5 


37.20 


6200 


li 


120 


200 


6 


6000 


1 0000 


2 


280 


480 


8 


12800 


21600 


2h 


528 


880 


10 


23200 


39000 


3 


900 


1500 


12 


37000 


62000 








14 


54000 


92000 



10 



For any other length, multiply values in table by ~t=' For 
a single pipe system the pipe should be about 50 per cent larger 



DIRECT STEAM HEATING 139 

than the steam pipe for a double pipe system. Never use a 
smaller steam main than ij ins. or a smaller return than i in. 

Another method is to determine the amount of steam required 
for a given amount of radiation, and after finding the volume 
of this steam, determine the area of the pipe to give a definite 
velocity. For large mains of 8 ins. or over 6000 ft. per minute 
may be used, while for smaller mains a velocity of 3000 ft. per 
minute. This may be written as a formula: 

i44Ahs 2.4Ahs , 

a = area of pipe in square inches ; 
A =area of heating surface in square feet; 
/j = transmission constant for the heating surface in B.t.u. 

per square foot per hour; 
5 = volume of i lb. of steam in cubic feet; 
Zr = heat content of steam in B.t.u. per pound; 
g = heat of liquid of condensed steam in B.t.u. per pound; 
Vel. =vel. of steam in feet per minute. 

In determining the diameter of the pipe, the table of actual 
areas on page 86 should be used rather than solving for the 
diameter of the circle of area a. 

The best method of determining the area of pipe to carry 
a given quantity of steam is to assume the allowable drop in 
pressure in the given length, and then to use the method given 
in the Transactions of the American Society of Mechanical 
Engineers, Vol. XX, p. 342, by R. C. Carpenter and E. C. Sickles. 
The formula derived in this paper is 



^ = loss of pressure in pounds per square inch in length 

of Lft.; 
X = constant = 0.0027 ; 
d' = diameter of pipe in inches ; 

D = weight of i cubic foot of steam at given pressure;, 
W = weight of steam in pounds per minute. 



140 ELEMENTS OF HEATING AND VENTILATION 

This may be written: 

^ = o.oooi3i(^i+^j^^7-, (64) 

or 



io.oooisi(i+^ ]W'^L 



^'=V '-Dp-^ (65) 

In this the value of d^ in the bracket is assumed for the first 
approximation, and then after substitution of this value within 
the radical a second approximation is found. The table given 
below has been prepared by the author for the weight of steam 
at 5 lbs. gage pressure which will be discharged for a J lb. drop 
in the length given. If the pressure or drop is different from 
that given, the weight of steam at a pressure of 5 lbs. and a drop 
of ^ lb. equivalent to the actual steam is given by 



/ 0.049XI / 0.012 



(66) 



To use lengths different from those given in the table, 
it is to be remembered that p varies as L and W varies inversely 
as \/L. 

The paper of Carpenter and Sickles gives the loss in pressure 
in one globe valve to be equal to the loss in 700 diameters of 
the pipe, while an elbow gives a drop in pressure equal to that 
from 520 diameters of pipe. 

To show the application of the table, suppose it is required 
to deliver 240 lbs. of steam per hour at 10 lbs. gage pressure 
through a pipe 45 ft. long, with 2 elbows and a gate valve with 
a drop of not over ^ lb. 

To find the equivalent steam per minute at 5 lbs. pressure 
and I lb. drop, the formula (66) is used (Z) = 0.0607 f^J" 10 lbs. 
steam) . 



240 / 0.049 X} 



DIRECT STEAM HEATING 



141 



FLOW OF STEAM IN POUNDS P£R MIN. AT 5 LBS. GAGE PRESSURE 
WTTH i-POUND DROP 



Diam. 








Length in Feet 








Inches 


25 


50 


75 


100 


150 


200 


300 


500 ' 1000 


3 
4 


0.51 


0.36 


0.29 


0.25 


0. 21 


0.18 


0.15 


. 1 1 1 . oS 


I 


1. 00 
2.46 
3 04 


0.72 
1. 61 

2.05 


0.58 
1-31 

1-75 


0.51 
1. 14 

1-52 


0.41 

093 
1.24 


0.36 
0.81 
1.07 


0.29 
0.66 
0.88 


0.23 

0.51 
0.68 


0.16 
0.36 
0.48 


2 
2| 


7.09 
II .70 


5.02 
8.33 


4.09 
6.79 


3-54 
5 89 


2.89 
4. So 


2.51 
4.16 


2.04 
3-39 


1-59 

2.64 

4.78 

10.10 


1. 12 
1.86 


3 

4 


21 .40 
45.60 


15.10 
32.20 


12.30 
26.30 


II .40 
22.80 


8.72 
18.60 


16.10 


6.18 
13.10 


7.20 


5 
6 


84.80 
138.00 


60.00 
97.60 


48.80 
79.60 


42.40 
69.00 


34.60 
56.30 


30.00 
48.80 


24.40 
39.80 


19.00 
30.90 


13 40 
21.80 


7 


202 . 00 


144.00 


118.00 


102.00 


83.00 


72.00 


58.80 


45.60 32.20 


8 


290.00 


205.00 


167.00 


145.00 


118.00 


103.00 


84.00 


65.00! 45 90 


10 


525 00 


371.00 


302 . 00 


262.00 


214.00 


224.00 


151.00 


117.00 83.00 


12 

14 


885.00 
1260.00 


627.00 
891 .00 


511.00 
726.00 


443 • 00 
630 . 00 


362.00 
514.00 


314.00 
445.00 


256.00 
364.00 


198.00 140.00 
282. 00! 199. 00 


18 


2370.00 


1680.00 


1370.00 


1190.00 


993 ■ 00 


862.00 


704 . 00 


595.00:385.00 


24 


5270.00 


3730.00 


3410.00 


2640 . 00 


2150.00 


1860.00 


1520.00 


1180.00^834.00 

i 



Assume as first approximation that L = so ft. Then from 
table d' = 2 ins. 



Then 



We for 200 ft. 



L=45+2x5-^=..sft.; 



12 



2.54^ 



\ — = 2.70; 
\ 200 ' ' 



d' from table, for second approximation = 2 ins. 

This pipe will be of sufficient size. 

To find the diameter by use of the table on page 138 it is 
necessary to change pounds of steam to square feet of heating 
surface. Roughly one quarter of a pound of steam is con- 
densed per square foot of surface per hour. 

/250 B.t.u. per square foot\ 
\ 1000 B.t.u. per pound /* 



240 lbs. of steam per hour will be consumed by 960 sq.ft. of 



142 ELEMENTS OF HEATING AND VENTILATION 

surface. From the table this requires a 3-in. pipe for the supply 
or a 4-in. pipe for a single pipe. 

Allowing 3000 ft. per minute as the velocity, the following 
method is used : 

240 lbs. of steam per hour = 7—: — 7— = 65.9 cu.ft. per minute; 

. 65.QX144 

A=^ ^ = 3.i6sq.m. 

3000 ^ ^ 

d^ = 2 ins. 

In this manner the size of the supply main to various risers 
may be found. The pipe is reduced at various points. 

To find the size of the return, an empirical method of using 
one-quarter of the area of the supply may be used until smaller 
sizes than 3-in. returns are found, when one-half the area may 
be used. In no case should a smaller size than i in. be used. 

As another method the volume of the condensed steam may 
be determined, and from this after assuming a velocity the area 
may be found. Chezy's formula may be used to find v, 

v = cVrs, (67) 

where 

c = coefficient = 75 for iron pipe about 4 ins. in diameter; 

V = velocity in feet per second ; 

, , - area pipe i ,, 

r = hydraulic radius m feet = — ——5 — — ;: ^ — = ~~s(i ; 

wetted perimeter pipe 48 

J' = diameter in inches; 

5 = slope of pipe in feet per foot ; 

V is about 2 ft. per second. 

The condensed steam is accomipanied by more or less air, so 
it is wel] to consider only one-half of the pipe as carrying water 
in the expression above. This gives the same hydrauhc radius. 
The volume of water is much greater per pound at high tem- 
perature, and this must be considered in determining the area 



DIRECT STEAM HEATING 



143 



to carry a given volume. The table below will be of assistance 
in this connection. 

WEIGHT OF WATER AT DIFFERENT TEMPERATURES 

Per Cubic Foot 



Temp. 


100° F. 


130° F. 


160° F. 


190° F. 


212° F. 1 220° F. 


Pounds per cubic foot 


6i .9 


61.5 


61 .0 


60.4 


59-8 


59-4 



In placing steam or return mains, care must be exercised 



11 



^ 



o 



3C 



o 



Horizontal Line 



Fig. III. — Drip Pots. 



to run the pipes with a decided pitch in one direction or the other. 
It is best where possible to pitch the pipe downward in the direc- 
tion of flow at least i in. in 30 ft. Where this is not possible, 
and the pipe rises in the direction of flow, it is advisable to 
install drip pots at intervals, which are drained as shown in Fig. 
III. This enables one to cut down the amount of water which 
is flowing back against the steam current, and being in condition 



144 ELEMENTS OF HEATING AND VENTILATION 

to be taken up by the steam current whenever there is a change 
in the demand for steam, changing the relative velocity of the 
steam and water. The endeavor should be made to drain in 
the direction of flow, but where this would lead to comphcations 
a . carefully designed line with the drainage in the opposite 
direction will give satisfactory results. 

The branches should be arranged to care for condensation. 
The branches to returns or drips should enter the tops of mains. 
In power plant work it is customary to take the branches from 
the top of the main to insure drier steam. The branches from 
the main in heating systems should be taken from the top when 
the line is at the bottom of the riser, but in the Mills' system 
it is better to take it from the bottom of the pipe, thus dripping 
the main at each branch. An examination of Figs. 99, 100, loi 
will show these arrangements. 

Care must be exercised to have no portion of a main below 
the extensions from each end of it so that condensation will 
collect in this part and stop the flow. Such pockets may 
prevent the circulation of steam in a low pressure system 
and in any case they may produce water hammer. Pockets 
if necessary in any part of the system must be drained. 
With a vacuum system small pockets may be cared for auto- 
matically by the pump, causing sufficient vacuum to lift the 
water. 

Valves are to be placed at high points in the line, globe 
valves being placed with the valve stems horizontal, while with 
gate valves the stems are vertical and the handle is placed 
above. These two positions prevent the water from collecting 
behind the valve. 

To prevent the formation of a pocket when there is a reduc- 
tion of diameter the regular reducer at A, Fig. 112, is replaced 
by an offset reducer B, or by on eccentric tee C, Fig. 112. 

The risers may be run exposed in the various rooms or they 
may be concealed in chases behind the plaster. The former 
method is advisable, as repairs may be easily made. For high- 
class work where pipes would be unsightly the latter method 
is used. In this case the pipes and fittings should be care- 



DIRECT STEAM HEATING 



145 



fully selected and the pipes should be tested before the plaster 
is put on. 

The radiator connections are best carried beneath the ceiling 
in the room below, although in concealed work they are carried 
in the space between floor and ceiling or directly under the floor. 
Concealed work is undoubtedly the more attractive, but when 
trouble is experienced there must be considerable cutting before 
repairs can be made. 

In many systems the air valves are connected to an air line 



Fig. 112. — Regular and OtTset or Eccentric Reducers. 



which discharges some place in the basement, as shown in Fig. 
113. The purpose of this was originally to deliver any drip 
of water into the sewer and not on the floor of the room. Lately 
it has been used in the Paul system for the attachment of a 
vacuum air pump to draw the air from the radiators, thus reduc- 
ing back pressure in a single pipe system. The objection to 
an air line is the fact that an improperly set air valve may 



146 



ELEMENTS OF HEATING AND VENTILATION 



deliver steam through this, thus interfering with the action 
of other valves and wasting steam unless the discharge end of 
the line is brought to a point where the attendant is sure to 
observe it. 

Pipe covering is used on pipes which are put in chases or 
are carried through spaces which are to be kept cool. The 
materials used are to be good non-conductors and substances 



^ 





J 



*— I: 



J 



I 



i 



n 



i 



n 



Fig. t 13.— Air Line. 



which will not burn or char. The substances used are 85 per cent 
magnesia, asbestos, hair felt, mineral wool and cork. The heat 
loss is found as for any conductor by the formula H =KA (ts—ta). 
Tests have been made by a number of persons to determine the 
values of these as heat insulators, and the results are similar. 
The table -below gives the results of Geo. H. Barrus as 
reported in the Transactions of the Society of Mechanical 
Engineers. 



DIRECT STEAM HEATING 147 

LOSS OF HEAT PER SQUARE FOOT OF PIPE SURFACE PER 
DEGREE DIFFERENCE IN TEMPERATURE PER HOUR IN B.T.U. 

lo-in. pipe, 150 lbs. steam pressure. 
Asbestos sponge felt, 76 laminations, .(if") 0.280 
" _ " _ " 66 " ..(i^") 0.306 

Magnesia, 13^ ins. thick o-354 

Asbestos navy brand (if") 0-3^7 

Watson's Imperial, i in. thick (asbestos 

paper) o . 428 

(Nonpareil cork o . 290) 

Bare pipe 3 . 220 

2 ins. pipe, 80 lbs. pressure. 

Asbestocel i in. thick o. 728 

New York air cell o • 75^ 

Carey's moulded i in o . 768 

Asbesto sponge molded i in 0-77^ 

Cast's air cell i in. thick o- 793 

(Nonpareil cork 0.512) 

Watson's Imperial o. 548 

These were reduced to same thickness of i in., and gave the 
following results : 

10 in. — 150 lbs. 

Asbesto sponge, 66 laminations 0.341 

76 '' 0.342 

Magnesia o . 394 

Watson imperial o . 428 

Asbestos navy board o . 472 

2 ins. — 150 lbs. 

Asbestos sponge hair felt, 3 ply 0.497 

'' " 2 ''■' 0.527 

Asbestos sponge felt, 59 laminations 0.527 

"48 " 0.531 

Magnesia 0.531 

Asbestos navy brand 0.652 



148 ELEMENTS OF HEATING AND VENTILATION 

These coverings save about 80 to 90 per cent of the heat which 
would be radiated from -the bare pipe. The covering will save 
its cost in less than half a year with steam at about 100 lbs. 
pressure. The kind of covering is an important item, as in many 
cases the more expensive covering will save much more than 
its original cost. 

The coverings are usually prepared in sectional form and 
appKed to the pipes in sections with canvas covers, as shown 
in Fig. 114, one section being an air cell covering, the other a 
solid covering. Each section is banded by at least two bands. 
At times blocks of covering are applied which are wire banded 




Fig. 114. — Pipe Covering. 

and then a hard plaster is applied to the surface, making a 
good finish. 

The covering costs about twenty to forty cents per square 
foot of pipe surface, depending on the diameter of the pipe, 
the smaller pipe costing more per square foot and will save from 
90 cents to 140 cents per year of 8760 hours with coal at $4.00 
per long ton. 

Using the tables of Chapter V, the various radiators for the 
rooms are found, and their positions determined from the plans 
and placed on the development of Fig. 105. After this is done 
the sizes of risers are determined by making the table as shown 
below, and then the sizes are marked on plans and develop- 
ment. The size of the supply is next found and marked on 
the plans. 



DIRECT STEAM HEATING 



149 



RESIDENCE OF L. Q. SMITH 



Riser. 


A. 


B. 


c 


D. 


E. 


Radiators 


la. 52 

7a. 48 

100 


lb. 52 
7b. 48 

100 


20. 36 

8a. 48 
84 


2b. 36 
36 


3a- I if 
ga. i6| 

28I 


Size 


xl 


i| 


ih 


il 


li 



Riser. 


F. 


G. 


H. 


/. 


J. 


Radiators 


4a. 42I 
loa. 20 

62I 


106. 20 
. 20 


iia. 20 

- 

52 


50- 32 

lib. 20 
52 


6a. 75 
12a. 14 

89 


Size 


li 


I 


li 


li 


li 



A table is now made to insert in the specifications, giving 
information to the contractor in regard to the kind, size, and 
location of radiators. 

FIRST FLOOR 



Room. 




Radiator. 


Heating 
Surface. 


Temp. 


Ratio. 


I 


la. 

lb. 


2 Column Peerless, 38 ins. 
38 '' 


52 

52 104 


70° E 


30 


2 


2a. 

2b. 


38 " 
38 " 


36 

36 72 


70° F. 


30 


3 
4 
5 


3a- 
4a. 
Sa. 
5b. 


23 " 
26 " 
20 " 
20 " 


Ilf 
42f 

32 

32 64 


70° E 
70° E 

70° E 


36 
32 

26 


6 


6a. 


45 " 


75 


70° E 


30 



150 ELEMENTS OF HEATING AND VENTILATION 

SECOND FLOOR 



Room. 


Radiator. 


Heating 
Surface. 


Temp. 


Ratio. 


7 


7(2. 


2 Column Peerless, 26 ins. 


48 








7&. 


< < ( < 


48 96 


70° F. 


30 


8 


8a. 


•38- 


48 


70° F. 


41 


9 


ga. 


32 - 


i6f 


70° F. 


45 


lO 


loa. 


20 '' 


20 








lob. 


20 " 


20 40 


70° F. 


42 ^ 


II 


iia. 


" 20 " 


20 








lib. 


20 '' 


20 40 


70" F. 


42 


12 


12a. 


20 " 


14 


70° F. 


34 






I 



iVi' 



l}£" 



6 Sec.-;22"Heatei> 



■2^' 



i-Jfh 



^ .--^tI b Risers 



^H 



-,\\\ss\ssss\sssss-ss^7:vr^ 



c Risers 



#7RJf 



-I^- 



Risers g 



r-<^ 



^^^^^^^^^^^^^^^^^ 



^Si 



i 



Fig. 115. — Cellar Plan of House for Dir ect Heatirg. 

With the table in the specifications and the development 
there is no ambiguity or chance for questions to arise in the 
completion of the work. Each bidder knows what is wanted. 
At this point it is w^ell to call attention to the fact that the heat- 
ing engineer should know that what he has designed is sufficient 



DIRECT STEAM HEATING 



151 





_2 

a 
c 

C 



152 ELEMENTS OF HEATING AND VENTILATION 

for the work and not to try to shift responsibihty by placing 
a clause in the specification that the contractor has to guarantee 
to heat the building to 70° in zero weather. If this is not accom- 
pHshed after specifying the amount of radiation it is clearly 
the fault of the engineer and not of the contractor, and the 
engineer should assume the responsibility. 

The cellar plan in Fig. 115 gives the arrangement of supply 
and return pipes in the cellar with the position of the boiler 
and flue. 

Fig. 116 illustrates a development of a larger building, show- 
ing the method used to fix the sizes of risers and mains. 



CHAPTER VII 



HOT-WATER HEATING 



In hot-water heating there are several methods of arranging 
the pipes. In one system there is a single-flow pipe or main, 
Fig. 117, in the basement from which supply and return risers 
are run to the different radiators. The flow pipe leaves the 



* 



n 



ft 



mr-^ 



t 



^i 





kp 



u 



^I 



i 



Fig. 117. — Hot Water with Single Main. 



top of the water boiler and re-enters at the bottom after making 
its completed circuit. The radiators used in hot-water instal- 
lations are usually made with the sections connected together 
at top and bottom as was mentioned on page 75, where the hot- 
water form of radiator was shown in Fig. 46. In a single-flow 
pipe system the water is gradually cooled as it passes through 

153 



154 



ELEMENTS OF HEATING AND VENTILATION 



the pipes owing to the cool return water being added. To aid 
the circulation and to keep the cold water from mixing too 
rapidly with the warm water, the branches to the supply risers 
are taken off from the top of the pipe, while the return is con- 
nected to the bottom of the pipe. For this purpose special 
tees are made and installed as shown in Fig. ii8. The supply, 
being taken from the top of the flow pipe first and then the 



r 



Supply 



[K.M 



liQil 



^ 



Retura 
Fig. ii8. — Eccentric or Offset Tees for Hot Water Main. 




Fig. iiq. — Flow Line Losing Y's. 



return from the bottom. Fig. 119 shows a method of using 
Y'S to accomplish a more positive circulation. 

The separate supply flow pipe and return flow pipe are shown 
in Fig. 120. In this the two pipes both rise as they leave the 
boiler, the supply from the high part of the boiler and the return, 
through a vertical leg from the bottom of the boiler. In this 
case there is no danger of getting the currents mixed and the 
branches may be taken from any part of the lines. In the figure 



HOT-WATER HEATING 



155 



the risers which are connected to the part of the supply near 

the boiler are at the far end of the return flow Hne. In this 




^FiG. 120. — Two-pipe Hot Water System. 




Fig. 121. — Branch Connections 



way the length of the various circuits may be equalized. Fig. 
121 shows one method of taking off branches from the flow lines 
when they are placed side by side, and there is not sufficient 



156 



ELEMENTS OF HEATING AND VENTILATION 



room beneath the joists to have one branch cross the flow pipe 
and to use an elbow on a tee pointing straight up with a close 
nipple. 

One fitting may be used as shown in Fig. 122 if the tee is 




Fig. 122. — Branch Connections. 

turned with the branch at 45° to the horizontal instead of in 
the horizontal position. In many cases there is not sufficient 
room to turn the tee vertically as shown in Fig. 123, and the 
methods of Figs. 121 and 122 are resorted to. This applies 
equally well to all forms of piping work for steam or water. 




n 



Fig. 123. — Branch Connections. 



The branch is sometimes taken below the flow line as shown 
in Fig. 124, when it is desired to have sluggish action, although 
air may collect in such a branch. The Honeywell Company 
advise the use of connections of Fig. 121, where a reduction 



HOT-WATER HEATING 



457 



occurs in the size of the main, using only a branch to a first-floor 
radiator. They never connect a high riser branch at such a 
point, as the circulation in such a riser at a reduction of section 
might cause excessive circulation in the section supphed by 
the riser. They recommend connections as shown in Fig. 124 
for all branches near boilers so as to cut down circulation at 
these points. Drips must be provided for draining the pockets 
formed in this branch when the system is being drained. If 
this is objectionable the branch shown in Fig. 121 may be used. 
In any case the endeavor must be made to have the circulation 
good in all radiators. 

The complete circuit system, Fig. loi, may be used for hot 




:o Radiator 



U^ 



I, .1 



Fig. 124. — Branch Connection. 



Risec 



7 



Fig. 125. — Riser. 



water as well as steam. In this the supply-flow pipe at the top 
of the building is fed from the top of the boiler through a riser 
and the return-flow pipe is placed at the bottom of the building. 
Of course in this case there are supply risers connected to the 
top of the radiators on one side while the return risers are con- 
nected to the lower part of the other side of the radiator. 

The risers are connected to the branches and in most hot- 
water installations there are no control valves on the branches 
to risers. 

If there are a number of radiators on a riser there is some 
danger of the circulation being established in the riser to an upper 
radiator and thus prevent a proper supply from reaching the lower 
radiators. There are several methods of avoiding this. One 
method, Fig. 125, is to place the supply to the radiator at the 



158 



ELEMENTS OF HEATING AND VENTILATION 



end of a section of the riser and continue the riser by means of 
a tee and an elbow. In this way there is resistance to upward 
flow due to the breaking of the direct path. In Fig. 125, if the 
radiator is assumed to the right and the continuation of the riser 
is assumed to the left the same result is accomplished. A third 
method is to reduce the riser diameter at the place where a con- 
nection is taken off to a radiator, the constriction throwing more 
resistance on the flow and thereby giving the lower radiator a 
supply of water. Fig. 125 shows the radiator connection lead- 
ing at right angles from the riser without a swing ell. This 
can be done in the case of hot-water work if the lines are not 





Fig. 126. — O. S. Connector. 



too long. The table in Chapter VI gives the expansion of 180° 
heating to be less than i in. to 100 ft. 

One of the best methods of causing water to flow into a lower 
radiator is to use the O. S. distributors, Fig. 126. These are 
special tees with a deflecting partition and in most cases a reduc- 
tion in size of piping on the run. 

When necessary to hug the wall of a building the branch may 
be taken off at an angle to the wall instead of parallel to it and 
by the use of a 45° ell, as shown in Fig. 127, the line is brought 
parallel to the wall. 

To find the amount of radiation for a hot-water system, the 
same method is used as for the steam system. The amount 
of heat for a given room from Chapter V is divided by the amount 



HOT-WATER HEATING 



159 



of heat transmitted per square foot of radiation for hot water 
and the result will give the amount of radiation. This number 
is about 170 B.t.u. per square 



Wall 



Wall 



foot per hour. Another result 
which is worth remembering 
is that I sq.ft. of hot water 
radiation requires i gallon of 
water or about J of a cubic 
foot or 8 lbs. of water per 
hour, as the drop in tempera- 
ture is about 20° F. 

After the amount of radia- 
tion is computed it is placed 
on plans and developments as 

in Chapter VI and then the pipe sizes are found. To check the 
results of the amount of heating surface the following table 
is given: 




Fig. 127. — Radiator Connection. 



ESTIMATED CUBIC FEET OF VOLUME HEATED BY 
FOOT OF HOT-WATER HEATING SURFACE 



SQUARE 



Residences : 

Living rooms 20 to 40 

Sleeping rooms 30 to 50 

Ofhces 30 to 50 

Schools 25 to 50 

Factories 40 to 80 

Assembly halls 45 to 90 

Hotels 50 to 70 

Stores 50 to 70 

Churches 80 to 1 20 

Auditoriums 80 to 1 20 

Gymnasiums 120 

Workshops • 130 

The size of the pipes in hot-water systems depends on the 
velocity of the water and the amount of water to be carried. 
The velocity depends on the height of the various radiators 



IGO ELEMENTS OF HEATING AND VENTILATION 

and the difference in the weight of the water on the hot side and 
the cold side. 

Suppose the height of a radiator from the return-flow pipe 
line is L ft. and the temperature of the supply is 4 and that of 
the discharge is ta. These are often about i8o° and i6o° respect- 
ively. Let the corresponding weights per cubic foot be Ds 
and Dd. The weight of water in the supply column is LADs 
and in the return is LAD a and that in the flow mains is 

L'A'( ^). A' is the area of the pipes in square feet and 

V is the length of each of the flow mains. The force in pounds 
causing flow is LADa — LADs. This is reduced to feet head 
by dividing by 

A(Da+Ds) 
2 

or 

If now this value for h be inserted in the formula 

(69) 

where 

7; = velocity in feet per second; 
^ = head in feet causing flow; 
^ = 32.2 = acceleration of gravity; 

/"= friction factor = 0.02; 

/ = total length of system; 
d = diameter of pipe (mean) ; 
n = number of bends ; 
m = friction factor for i bend = |, 

the velocity to be expected may be found. In this there 
will be varying velocities in the various risers so that in general 
an empirical table is used for the various risers after the amount 
of radiation is known. From the amount of radiation the amount 




HOT-WATER HEATING 161 

of water needed per hour may be found by the rules given above 
or to be exact the weight of water may be computed thus : 

W =^^ (70) 

qs-qa 

W 
^^1^ = A • ^^'^ 

W 
vold = ^ ^7^) 

PF= weight of water per hour in pounds; 
5" = heat to be given off per hour; 
q = heat of liquid at supply or return. 

Knowing the volume, the area of the pipe is given by 

. vol 



(73) 



68 


86 


104 


122 


I .000174 


1.00425 


1.0077 


I .0119 


158 


176 


194 


212 


I .0226 


I .0289 


I -0357 


I. 0431 



For use in computing problems, the following table is given. 

DENSITY OF WATER AT VARIOUS TEMPERATURES 

Temperature 50 

Rel. density i .00025 

Temperature 140 

Rel. density i .0169 

To apply the above to a given problem suppose 7500 B.t.u.'s 
are to be transmitted from radiators per hour in rooms 10 
20 and 30 ft. from basement floor, at which level the return 
water enters the boiler. The hot water is assumed at 180° 
and the return at 160° F. The radiators are arranged on 5 
risers. The flow pipes are 40 ft. long. 

I St. Heating surface approximate: 

4 75000 

A = — — =440, ■ 
170 ' 

or 88 sq.ft. per riser. 



162 ELEMENTS OF HEATING AND VENTILATION 

2d. Water per riser: 

75000 I 

wt. = =750 lbs. per hour; 

5 148 — 128 '^ ^ ' 



7 SO 

vol. = -^ — =11.7 cu.ft. per hour; 

1.03X62.5 ' 



3d. Velocities to different floors: 



i.oso — 1.02^ ^^ ^ 

hi = 20 — ^— -^ =0.068 ft. 



1. 030 + 1.023 

/?2 = 4oX.oo34 =0.136 ft.; 

/?3 = 6oX.oo34 = 0.204ft.; 



2X32.2X0.068 ^^ . 

.1= ^^^:^ -=0.66 ft. per sec; 

Vo.o2X ^^ 7 +8Xi 



z;2 = o.89 ft. per sec. 
1^3 = 1 .03 ft. per sec. 

These velocities in ft. per min. are respectively: 39.6, 53.4, 
61.8. 

The velocities will practically increase with the square 
root of the height. 

4th. Areas of pipes: 

Using mean velocity of 0.9 from V2, the following results: 

Area of riser m square mches = — ,, . =.^2 sq.m. 
^ 0.9X3600 ^ ^ 

This gives a f -in. pipe in which the resistance is much greater 
than in a 2-in. pipe used in computing V. Hence a recalculation 
should be made giving a large pipe. 

This method is not used, as it is lengthy and instead a table 
such as that given below is employed generally. 



HOT-WATER HEATING 



163 



SIZE OF PIPES FOR HOT-WATER MAINS AND RISERS 



Sq. Ft. of 
Radiation. 




Mean Height of Radiators. 




10 


20 


30 


40 


50 


I inch 


I inch 


I inch 


I inch 


100 

150 
200 
250 


2 " 
2 " 


I " 


A 2 


I " 
I " 


300 


2 " 


2 " 


l| " 


i| '' 


400 


2i " 


2 " 


2 " 


2 " 


450 


2h " 


2| " 


2 " 


2 " 


500 


3 " 


2h " 


2 " 


2 " 


1000 


4 " 


3 " 


3 " 


3 " 



Using the table the problem above would require a i-in. 
pipe for 88 sq.ft. for a mean head of 20 ft. 

The flow lines are found for the total amount of radiation 
or water. 

The Honeywell Company determine sizes of risers and flow 
pipes by adding together the areas of valve openings or areas 
of radiator connections used on any riser or supplied by the flow 
pipe. Their valve sizes or drilling sizes are smaller than those 
recommended by others, as seen by comparing tables on pages 
163 and 168. Thus in the problem above they would use a 
f-in. riser. 

The connections to the radiators are fixed by the drilhng table 
of the radiator manufacturers as given in Chapter VI. The 
drillings for the water radiator are repeated. 



SIZE OF OUTLETS FROM RADIATORS 


Sq. Ft. of Radiation. 


Supply and Return. 


40 
40-72 

72 


I Xi 

liXii 

liXiJ 



Air valve vent tapping \ in. 

Although the best circulation is obtained when two valves 
are used on hot-water radiators, a single valve, Fig. 128, may 
be used. This is known as the Honejrwell iinique valve. 



164 



ELEMENTS OF HEATING AND VENTILATION 



The supply goes in one side of the valve and enters the 
radiator, being kept from short circuiting to the return by the 
partition which extends into the radiator. This permits the 
water to rise through the first section of the radiator and fall 
through the remaining sections. The handle moves a diaphragm 
which separates the two elbow openings in the valve, causing 
the water to pass in on one side of the partition and out of the 
other. A turn of one-sixth of a revolution causes the diaphragm 




A 



ooooo ooooooooo ooooc 



!2f 



cooooooo o o tf oo o o ooooo 



Fig. 128. — Honeywell Valve. 



Fig. 129. — Expansion Tank 



to cut out the opening to the radiator and connect the two 
elbows, by-passing the radiator. 

In this way the circulation through the supply and return is 
never interfered with. This valve can be used with the complete- 
circuit system, the supply elbow being turned up and the return 
down. There are several advantages in having the connections 
at one end; the radiator may be enlarged; the cutting is at 
one place and the two risers may be kept close together. 

Since water expands about 3 per cent in being heated to 
180° F. it is evident that there must be some provision to care 



HOT-WATER HEATING 



165 



for this expansion, and hence all hot-water systems are provided 
with an expansion tank, Fig. 129, or its equivalent. The 
expansion tank is connected to a riser A at the highest part of 
the system and is provided with a w^ater gage to show the level 
of the water and a vented overflow^ B leading to the sewer. 

This tank should be of such a volume that the expansion 
of cold water, say at 70° F., to the higher temperature, say of 
200° F., will cause the water to rise from near the bottom of 
the tank to the top of the tank or to the top of the water column. 
The size should be such that the latter is true, then at all times 
the level of water is shown. If the water level cannot be seen 




t 

C B A 

Fig. 130. — Expansion Tank with Float. 

the small cock at the bottom of the gage may be opened to indi- 
cate whether water is present or not. When water is low in 
the tank the water is usually fed into the system from the city 
supply, which is connected where the return water enters the 
boiler. 

Another method to ensure the system being kept full of water 
is to have a tank. Fig. 130, with a ball float attached to the high 
part of the hne. Then as the water rises it is carried off by the 
overflow A, while if the water contracts more water is fed into 
into the system from the tank through B, the ball float control- 
ling the admission as the level falls. 

These tanks are placed at a high part of the system, but it 
should always be in a warmed room, so that there is no danger 



166 



ELEMENTS OF HEATING AND VENTILATION 



of the expansion tank freezing. The freezing of the tank would 
not only endanger the tank, but it will prevent expansion of 
the water as it is heated, thus bringing undue strains on the sys- 
tem and rupturing radiators or boiler. 

If a water closet is on the top floor of a building, the water 
tank of the closet may be used as an expansion tank, as this will 
always have water over the bottom of the tank. 

The size of the tank may be found by computing the water 
content of the system and then using 3 per cent of its volume 
as the volume of the tank. In general, however, the tank may 
be proportioned by the amount of radiating surface by the table 
below : 

EXPANSION TANKS 



Size. 


Gallons 


Sq. Ft. of 


Size. 


Gallons 


Sq. Ft. of 


Capacity. 


Radiation. 


Capacity. 


Radiation. 


10X20 


8 


250 


16X36 


2>2 


1300 


12X20 


10 


300 


16X48 


42 


2000 


12X30 


15 


500 


, 18X60 


66 


3000 


14X30 


20 


700 


i 20X60 


82 


5000 


16X30 


26 


950 


22X60 


100 


6000 



The maximum temperature carried on a hot-water system 
is fixed by the height of water carried on the boiler. Thus if 
the level of the expansion tank is about 40 ft. the water at the 
boiler could be 250° F. before it could boil, due to the pressure 
on it, but as soon as this heated water had reached a higher 
level, part of it would turn into steam and drive the water out of 
the expansoin tank. In most cases when the water gets beyond 
220° F. there is danger of driving the water out of the system. 

To enable one to carry a higher temperature in very cold 
weather the Honeywell Generator, Fig. 131, is used. The point 
A is connected to the heating system, preferably near the boiler. 
As the water in the system is heated it expands into the chamber 
B driving the mercury C into the circulating tube D and the 
standpipe E. By the time the mercury reaches the top of the 
circulating pipe the lower end is open to the water and this 
rises through the mercury, causing an upward flow, the mercury 



HOT-WATER HEATING 



167 



which is discharged into the separating chamber F falling 
back through the standpipe E. If the discharge is at all violent, 
the baffle plate G will deflect the mercury downward. The water 
then passes through H to the 
expansion tank. 

When the system cools 
off the contraction of the 
water causes the mercury to 
be forced up in B, allowing 
water to flow back through 
H and E and passing up 
through B it separates from 
the mercury and leaves at A . 

By this arrangement it is 
seen that the water in A 
and B may be under at least 
a pressure produced by a 
column of mercury equal to 
the height of the circulating 
tube. This usually amounts 
to about lo lbs. per square 
inch. In this way the press- 
ure on the water in the 
system may amount to lo 
lbs., permitting the tempera- 
ture to reach about 240° F. 

The Honeywell Company 
claims that this device will 
accelerate the flow of water 
through the system even 
under low temperatures. 
This device does not increase 
the driving force unless the 
temperature is increased, as 
the system is closed, there being the same static difference of 
pressure throughout the system due to temperature dift'erence, 
but in case of need the possibility of getting a higher tem- 




FiG. 131. — Honeywell Generator. 



168 ELEMENTS OF HEATING AND VENTILATION 

perature on one side means that there can be more difference 
between the weights of the water in the ascending riser and in 
the return riser, and hence there may be a more rapid circula- 
tion. The generator is a very ingenious and vakiable device 
for increasing the temperature of the water and thus the value 
of each square foot of radiation, and at the same time increasing 
the unbalanced pressure due to the difference in density of the 
hotter water, so that smaller pipe may be used. It will do this 
with safety. 

The drilHngs recommended by this company for radiators 
are as follows: 

First Floor 

Up to 30 sq.ft J inch 

30 to 75 '^ i '' 

Over 75 '' I '' 

Second Floor 
Up to 40 sq.ft i inch 

40 to 100 4 

Over 100 ' ' I ' ' 

Tpiird Floor 

Up to 50 sq.ft J inch 

50 to 125 '' i ^' 

Over 125 '' I '' 

The valves of the radiators at the ends of the mains are made 
one size larger than those given in the table. 

These sizes are much smaller than those given in the earlier 
part of the chapter and the areas of risers and mains which are 
made equal in area to the areas of the connections which they 
supply are also smaller. This is possible because in times of 
need the temperature may be increased to such a point that the 
circulation is rapid enough to care for the heat needed. 

Small pipes are cheaper, but beyond that there is no advantage 
in the small pipes except that because the amount of water in 
the svstem is less, the time taken to get the radiators heated is 



HOT-WATER HEATING 



169 



not great. Against this, however, the fact must be remembered 
that the system of small water capacity will cool quicker. The 
heat put into the water, whether the mass be great or small, is 
to be taken out by the radiators, so that the volume of water 
in the system should not affect the economy of the system. 

The method of attaching the generator to one of the upper 
radiators of a system which has been installed is shown in Fig. 




Fig. 132. — Generator Connection. 



132. In this a branch has been taken from the supply of a unique 
valve and carried to the generator, which is then connected 
to the expansion tank. In no case should the generator be 
placed close under the expansion tank. The pressure produced 
in the system is independent of the position of the generator. 
The same water column is acting in addition to the mercury 
wherever it is placed. 

Using the methods given above on the plans of the residence 



170 



ELEMENTS OF HEATING AND VENTILATION 



and the tables of Chapter V, the amount of radiation for the 
various rooms may be found. These are given in the table below : 



Room. 


Sq.Ft. 


Kind. 


Room. 


Sq.Ft. 


Kind. 


I 


170 


3 col., 38 ins. 


7 


157I 


3 col., 26 ins. 


2 


120 


3 col., 38 " 


8 


75 


3 col., 38 " 


3 


21 


3 col., 22 " 


9 


22^ 


3 col., 32 " 


4 


7ii 


3 col., 26 " 


ID 


66 


3 col., 22 " 


5 


90 


3 col., 20 " 


II 


66 


3 col., 22 " 


6 


126 


3 col., 45 " 


12 


27 


3 col., 22 " 



These are now placed on the development, and the cellar 



^ 



gJ-f 






Risers a 



m 



Risers b 1}4 



^h" 



[IT 



q-1^- 



3 Risers j 
134" 



5 Sec.22 Heater 



^^i^^^^ 



2k 



■.^s^s^^^^s^^^^ss^s 



Risers c 



2^- 



Wz 



^^mm 



-W2- 



Risers e 



4;^^$^$^^^^ 



31^ 



-3^ 



1^1 



ip 



Risers i ^^ Risers ^i 



IH 



JK 



^ 



Risers/ Risers g ± 



^^$5;$;$$^^^$^ ^^^^^ 



Fig. 133. — Arrangement of Pipes and Boiler for Cellar with Hot Water. 



plan, Fig. 133, is made to show the arrangement of flow lines 
and boiler. 

The table below gives the surface on each riser and the size 
of the same. 



78 78 153 

^iff ,in ^j'l 



Risers 


a. 


b. 


c. 


d. 


e. 


/. 


g- 


Surface 


163! 


163I 


135 


60 


43l 


i04i 


2>2, 


Size. . . . 


.ir 


ir 


li" 


l" 


1" 


li" 


1" 



CHAPTER VIII 

INDIRECT HEATING 

As mentioned in Chapter I, there are three general methods 
of indirect heating. First, the natural-draft method, in which 
heating coils are placed in boxes at the bases of flues leading to 
a room or group of rooms. This is used in small installations 
or residences. Second, the plenum or forced mechanical 
method in which air is drawn over heating coils and forced 
into the various parts of the building to be heated, thus pro- 
ducing in the rooms a pressure slightly above the atmosphere. 
Third, the vacuum system in which air is drawn from the 
rooms to be heated by a fan, inlet air passing from the outside 
over coils of pipe. In all of these methods air is used to convey 
the heat and in all but the first method there may be con- 
siderable force to give this air a definite path. In the first 
method the heaters are placed at the bottom of vertical risers, 
so there is little resistance to the flow of air, and this method 
gives good results. The boxes are placed at proper locations 
through the basement and supplied with steam from a boiler 
at some convenient point. There is no trouble experienced 
in passing steam to remote indirect radiators. The second or 
plenum method has the advantage of keeping the building 
under a pressure above the atmosphere so that leakage is out- 
ward, while in the vacuum system there is a constant leakage 
of cold air into the room through all loose windows or doors. 
There are cases, however, where the vacuum method is the 
only one which can be used, and hence the student should 
understand its peculiarities. 

The method of procedure for the design of indirect installa- 
tions is best illustrated by an application to a given building. 
The house used in Chapter V will be investigated according 
to the method of separate heaters. 

171 



172 ELEMENTS OF HEATING AND VENTILATION 

In the indirect system the amount of air for ventilation is 
first determined, then the temperature of this air is found so 
that it will supply the heat losses to the room when the air is 
cooled off from the inlet temperature to the temperature desired 
in the room. After this, the amount of heating surface needed 
is computed and finally the size of the duct to properly carry 
the air is determined. These steps are common to all three 
indirect methods of heating. If the temperature of the entering 
air h (or Ti absolute) is too high for convenience or comfort, 
it will be necessary to increase the quantity of air beyond that 
considered necessary for ventilation. 

The temperature of the air fixes the number of rows of coils 
or heaters in the mechanical system, although in the natural- 
draft system one set of indirect heaters is usually sufficient, as 
the velocity over the radiators is low. The curves of Chapter 
IV give these data. 

If the quantity of air per hour is V cu.ft. and the amount 
of heat lost from walls and windows per hour is h in B.t.u., 
the following equation holds: 

h=Vc{ti-tr) (74) 

c = heat necessary to raise i cu.ft. 1° F; 
/i = temperature of entrance; 
tr = temperature of room. 

Hence 

/l=^r+pr^ (75) 

now as has been noted earlier in the text 

0.237 Xi44><£& • ^ 1 / /:^ 

'= R{t+4S9-^) =0.02 approximately . . . . (76) 

^ = 53-34; 
^ = mean temperature of air in deg. F. = T° absolute; 
/?6 = barometric pressure in pounds per square inch. 



INDIRECT HEATING 173 

This neglects the effect of vapor in the air, although that 
should be considered for great accuracy. The reason for this 
is the fact that if the vapor is considered in finding c for the 
mixture, it must be considered in Eq. (74) giving an additional 
term, although the value of c would be smaller. The net result 
would be slightly different from the above and hence this 
approximate method is sufficiently accurate for this type of 
problem. 

It will be seen that the heat in the air above the room tem- 
perature is sufficient to care for the heat losses, as in most cases 
the hot air is dehvered across the ceilings against the cold walls 
before it mingles with the air of the room, and hence by that 
time it is reduced to room temperature, and when it returns 
to the bottom of the wall from which it was discharged so as 
to pass out through the vent flue to the roof it is as the tem- 
perature of the room. 

In computing this temperature of entrance h for various 
rooms in a system, it is found that the value is quite different 
for different rooms, because the quantities V and h vary in dif- 
ferent ways; V for one room may increase over that in another 
if more people occupy the room, while h might be smaller if 
that room were not exposed as much as the other room. For 
this reason it is not possible to run a main duct from the heater 
in the plenum or vacuum systems and take from it the flues 
to the various rooms. One of two methods must be used. 
In the first method a pair of ducts must be run in the basement, 
one carrying hot air and the other warm air, and from them 
connecting branches are run to each flue with mixing dampers, 
so that the proper amount of each may be had to give the desired 
temperature. In the second method a separate duct must be 
taken to each flue from the heater where both warm and hot 
air are supplied through mixing dampers to give the correct 
temperature to each duct. 

The first method is known as the double-duct system and 
the second, the single-duct system. These were described on 
page 13. The requirement of air at two temperatures makes 
it necessary in both of these arrangements of mechanical ventila- 



174 ELEMENTS OF HEATING AND VENTILATION 

tion to install two heaters, one known as a tempering coil, to 
heat all of the air to a low temperature and the other to heat 
a portion of the air to a higher temperature after separating 
the air into two parts. One temperature might be fixed by the 
highest temperature necessary, the other by the lowest tem- 
perature necessary. 

In the natural-draught method of indirect heating there is 
not the necessity of having the two temperatures, as the air 
from each box passes to its own room or group of rooms. In 
this system the main problem of design is to get sufhcient sur- 
face to give the heat necessary for the room and to get sufficient 
air for ventilation. Since the air enters at about ioo° F. the 
velocity for different heights of flow may be worked out as 
follows : 

Weight of L ft. of air at temperature h of i sq.ft. cross- 
sections : 

^'^R(h+^s^r~RTr ^77) 

(r is absolute temperature). 

Weight of L f t. of air at the temperature of the outside air : 

w^=^^rr^, = "-^ (78) 

The head causing flow is the difference of these if expressed 
in pounds per square foot, or if divided by the weight of i cu.ft. 
of air at the flue temperature it gives the head in feet of air. 

The weight of i cu.ft. of hot air is 

144^ 144^ . X 

^'=m^^^)=-Rf; (79) 

Hence the head in feet of the hot air which is flowing through 
the pipes is 

_ , L{T,-To) L{T,-To) 

Head = — ^fr^ — Ti = 7^^ . . . (80) 



INDIRECT HEATING 175 

This head is used in causing a velocity v in the hot air and 
overcoming friction. Using the general hydrauhc equation for 
the flow of a fluid the f oUowing results : 

Head = — ( i+y^+wm+/-^) (8i) 

?; = velocity in feet per second; 
^ = coefficient for entrance loss = J; 
n = numbers of bend ; 
m = coefficient for i bend = 0.2 ; 
/= friction factor = 0.02; 
I, = length of pipe in feet; 
d = diameter of pipe in feet ; 

^ = acceleration of gravity = 3 2. 2 ft. per sec. per sec. 
If the bracket be called Z the following results : 



hg Head / L{T\-To)- ._ , 

For ri = 56o, To = 460, andZ = 2; this becomes 

z; = 8.o2Vo.iiL . (83) 

These values of V for different floors are then as follows: 

v = 6 ft. per second for 5 ft. ; 
i; = 8.4 ft. per second for 10 ft.; 
z; = ii.9 ft. per second for 20 ft.; 
2^ = 14.6 ft. per second for 30 ft.; 
z;= 16.8 ft. per second for 40 ft. 

Although these .values have been computed with friction, 
the usual values taken in design are considered at about 
half of these: i.e., 3 ft. per second for first floor, 4.2 ft. per 
second for second floor 5.8 ft. per second for third floor and 
7.3 ft. per second for fourth floor. 

Having the velocity for any floor and the amount of air 
required, the size of flue may be found. 

V 

A=—^ . (F = cu. ft. of air per hour) . . (84) 

36002; ir / \ -r/ 



176 ELEMENTS OF HEATING AND VENTILATION 

The amount of heating surface will depend on the amount 
of heat required and the rate of heat transmission. Adding 
together the heat for ventilation and that for losses as found 
in the tables of Chapter V, the total amount of heat is known. 
The heat transmission per square foot of area of indirect surface 
depends on the velocity and until this is known only an approx- 
imate value can be had. Assuming this to be 300 B.t.u. 
the surface required will be given by 

5 = --. , , (85) 

300 ^' 

If now the area between the sections to give this surface 
be found then the velocity may be found : 

V 
v = — — r (86) 

^7, = Area of passages in heater. Experiments seem to 
indicate that with natural draft radiators the heat transmis- 
sion coefficient equals the square root of the velocity. This 
means 



».=vj[,.-fi=±ii] 



(87) 



/?i=B.t.u. transmitted per hour per square foot; 
ts = temperature of steam or mean temperature of water 

in degrees F. 
/o = temperature of outside air; 
ti = temperature of air entering room; 
2; = velocity over coils in feet per second. 

In this way the heat per square foot may be found and from it, 
the surface. It may be necessary to make two approximations 
before the area found agrees with that required to give the 
hi assumed. 

After this is computed the ducts leading to the outside are 
found. In determining these the velocity should be assumed to 
be that in the inlet passages. In fact this velocity might be 



INDIRECT HEATING 



177 



assumed to be the velocity over the coils or sections of the 
heater and the distance between sections so made that this is 
obtained. In figuring areas for cold air the volume of this air 
must be found. 

The application of this method to room i of the house leads 
to the following: 

Volume air per hour 6200 cu.ft. 



h = 



16810 



6200X0.018 



4-70 = 226° F. 




Fig. 134. — Cellar Plan for Indirect Heating. 

This is too high, so the quantity of air must be increased. 
Assume this to be six changes per hour. 



h = 



16810 



f 70 = 120° F. 



18600X0. 018 
This is a possible value. 

Z?' = 16810 + 70X0.018X18660 = 40300. 



178 ELEMENTS OF HEATING AND VENTILATION 
Velocity 4 ft. per second. 

7 ./"/ 0-|-I20\ 

;/=V4(^227- — ^j=334; 

40300 
6 = = 120 sq.ft.: 

334 

18660X144 a..' 

An= — :— -7 = 186.6 sq.m. 

4X3600 ^ 

The table below gives the data for the complete house and 
Fig. 134 illustrates the layout in cellar to accomplish the 
result. 







Ventilation. 




















Heat 
Loss. 






'^ 


Total 
H. 


V 


h 


s 


Actual 


Area 
. Flue. 




Room 






Ratio. 






Chap. 
V 


Used. 


















I 


16810 


6200 


18600 


.20 


40300 


4 


334 


120 


120 


187 


26 


2 


II792 


4300 


14000 


117 


29400 


4 


334 


90 


96 


140 


22 


3 


1745 


800 


2000 


118 


4300 


4 


334 


13 


16 


20 


25 


4 


6890 


2800 


8000 


113 


16900 


4 


334 


51 


56 


80 


25 


5 


8740 


3200 


1 0000 


119 


21300 


4 


334 


64 


64 


100 


25 


6 


10635 


3200 


12000 


119 


25700 


4 


334 


78 


80 


120 


27 


7 


14050 


2910 


16000 


119 


34100 


5.6 


394 


87 


88 


114 


33 


8 


8750 


2000 


1 0000 


119 


21300 


56 


394 


54 


56 


72 


36 


9 


2170 


720 


3000 


no 


5700 


5-6 


394 


15 


16 


22 


44 


10 


7680 


1700 


9000 


117 


19OCO 


5.6 


394 


48 


48 


65 


26 


11 


8330 


1710 


1 0000 


116 


21000 


5-6 


394 


53 


56 


72 


25 


12 


2840 


480 


3500 


115 


6000 


5-6 


394 


15 


16 


25 


19 



* Using Junior Indirect Radiators. 

The ducts leading the air to the boxes, the boxes and the 
flues are made of galvanized iron, although in many cases the 
flues are made of tin as will be given more in detail in the next 
chapter. Each duct leading to the outside should have a slide 
so that cold air may be cut off should there be any danger of 
the steam being shut off. A damper should be put in each duct 
and it is well to have register faces with closing flaps. 

The galvanized iron should be of proper gauge to give suf- 
ficient stiffness. For round pipes the manufacturers of heating 
apparatus recommend the following: 



INDIRECT HEATING 179 

Diameter. Gauge. Rectangular. 

up to i8'' 26 up to 6X6 

19 to 24'' 24 7X7 to 12X12 

30 to 39^^ 22 13X13 to 20X20 

40 to 49^^ 20 21X21 up 

50 to 70'' 18 

For rectangular ducts the limiting square is given. The 
guage used is the U. S. standard sheet metal gauge. The gauge 
numbers stand for the following thicknesses: 

Gauge No 28 26 24 22 20 18 16 14 

Thickness qt iIo 10 32 30 20 Te er 

Gauge No 10 8 6 4 2 o 000 

1 niCKneSS 64 64 64 64 64 16 8 



nnnnnnnnnnnnnn 

""nnnnnnnnnnnnn 
nnnnnnnnnnnnn 
pnnnnnnnnnnnn 
nnnnnnnnnnnnn 
nnnnnnnnnnnnn 
nnnnnnnnnnnnnn^ 
nnnnnnnnnnnnnn 



nnnnaannnnnnnna ® 






Fig. 135. — Register Faces. 

The register faces are of various sizes and designs. Fig. 135 
illustrates two typical forms of these. They are usually made 
with dampers. They vary from 4X6^^ around body (sf X7f 
extreme size), to 38X42'^ (4o|X44 8)- The variations are by 
I to a!' on a side so that almost any size may be obtained. For 
special work large sizes may be had. 

The net area of the register amounts to about 66 per cent 
of the box or body area. 

A school building has been selected to illustrate the method 
of calculating a plenum system, on account of the small quantity 
of air required for a house. After this the method will be apphed 
to a shop building. 

Figs. 136, 137 illustrate the basement and second floor 
of a school building. There are three floors to the school, all 
floors being the same. 



180 ELEMENTS OF HEATING AND VENTILATION 



The amount of ventilation has been computed by allowing 
1800 cu.ft. per pupil, which is the amount required by law in 




Fi3. 136. — Basement of School No. 3, Rydal, N. Y. 




Fig. 137. — Second Floor of School No. 3, Rydal, N. Y. 

some States. This is rather a large amount, especially in the 
lower grades and could be reduced if it were not for the law. 



IXDIEECT HEATING 181 

The amount required by various authorities has been given in 
Chapter II. 

The heat loss from the various rooms considering the exposure 
and other elements has been computed in a manner similar to 
that described in Chapter V and the results of this computation 
are shown in the table on page 182. 

The temperatures assumed for this school have been 70° in 
zero weather. The column marked "air temperature" gives 
the tem.perature of air entering the room from the flue. 

The first computations to be made are those from the 
heater. The temperatures of the hottest air and coolest air 
show that the air could be heated to 71° F. and a portion to 
89° F. Then by properly adjusting aU dampers the necessary 
mixture temperatures could be had. In the present instance, 
though, the temperature of the tempered air will be 70° F., 
and the remainder will be heated to such a temperature that the 
total heat will be equal to that required for the building. 

Total heat for building =3,052,000 B.t.u. 

Heat for tempering coil =2,541,000 B.t.u. 

Heat from main coil = 511,000 B.t.u. 
Temperature of air discharged from ^^^ 

main coil if one-half is heated = '- 7 +70° 

o.o2Xi8i5ooXi ' 

= 98° F. 

The problem will be worked out using Vento heaters and then 
with pipe coils, the steam being at 5 lbs. pressure in zero weather. 

From the Vento heater curves, Figs. 89-90, it is seen that 70° 
is given by 2 sections at a velocity of 730 ft. per minute, or by 
3 sections at 1700 ft. per minute. From Fig. 91, i section of 4 
rows of pipes at 190 ft. per minute, 2 sections at 370 ft., 3 sec- 
tions at 800 ft., 4 sections at 1600 ft. would give a temperature 
of 70° if pipe coils were used. 

The high velocities would mean much friction and the low 
velocities would probably require too much space. The velocity 
of 1000 ft. per minute is a fair value, so that in the problem 
the velocity of 730 might be used for the Vento heater and 
800 ft. per minute if pipe coils are used. These values will be 



182 



ELEMENTS OF HEATING AND VENTILATION 



Requirements for School No. 3 

RYDAL, N. y. 



First Floor 



Second Floor 



Room 


Occu- 


Cubic 

Feet. 

Ventila- 


Heat 


Air 


; Room 


Occu- 


Cubic 

Feet. 

Ventila- 


Heat 


Air 


No. 


pants. 


Loss. 


Temp. 


; No. 


pants. 


Loss. 


Temp. 






tion. 






[ 




tion. 






I 


49 


88200 


29100 


86 


7 


49 


88200 


29000 


86 


I. A. 




6000 


1800 


85 


7A 


— 


6000 


1800 


85 


2 


49 


88200 


27000 


85 


8 


49 


88200 


26000 


85 


2A 


— 


6000 


1500 


83 


8A 


— 


6000 


1500 


^2> 


3 


49 


88200 


21000 


82 


9 


49 


88200 


20000 


81 


3A 


— 


6000 


1500 


85 


9A 


— 


6000 


1800 


85 


4 


49 


88200 


19000 


81 1 


10 


49 


88200 


18000 


80 


4A 


— 


6000 


1500 


83 


loA 


— 


6000 


1500 


83 


5 


49 


88200 


33000 


89 


II 


49 


88200 


32000 


88 


5A 


— 


6000 


1800 


85 


iiA 


— 


6000 


1800 


85 


6 


49 


88200 


25000 


84 


12 


49 


88200 


24000 


84 


6A 




6000 


1800 


85 


12A 

! 




6000 


1800 


85 
75 


Halls 




60000 


1 0000 


71 


Halls 




30000 


3000 




Total 




625000 


174200 




Total 




595000 


162200 





Third Floor 



Room No. 


Occupants. 


Cubic Feet 
Ventilation. 


Heat Loss. 


Air 
Temperature. 


13 


49 


88200 


30000 


87 


13A 


— 


6000 


1800 


85 


14 


49 


88200 


28000 


86 


14A 




6000 


1500 


83 


15 


49 


88200 


22000 


83 


15A 


— 


6000 


1800 


85 


16 


49 


88200 


20000 


81 


16A 




6000 


1500 


83 


17 


49 


88200 


34000 


89 


17A 


— 


6000 


1800 


85 


18 


49 


88200 


26000 


85 


18A 


— 


6000 


1800 


85 


Halls 




30000 


4000 


77 








Total 




595000 


174200 










Grand total. 




I 81 5000 


510600 
2541000 




TTppt fnr air 


u 










Total heat B.t. 


3051600 













INDIRECT HEATING 183 

used, although in the remaining calculations it may be necessary 
to make a different assumption for the temperature of the tem- 
pered and heated air. 

From the curves of Chapter IV the heating value of the 
surface may be found. Fig. 90 gives the heat per square foot 
per hour at 730 ft. per minute with 2 sections as 1450 B.t.u., 
while 1750 B.t.u. will be given off per square foot of coil surface. 

The square feet of heating surface required for the temper- 
ing coil will be : 

For Vento heaters ~ '- = 1 7 so sq .f t. ; 

1450 ^^ ^ 

2,541,000 
For Buffalo Forge coils — = 1450 sq.ft. ; 

The area in square feet required through these heaters is 

-r- XT 1 1,815,000 . 

For Vento heaters — 7— =41.^ sq.ft.; 

730X60 ^ ^ ^ 

^ ., 1,815,000 
For coils -.^ — —7 — = ^7. 8 sq.ft. 
800X60 ^' ^ 

The data sheets for Vento heaters and coils of one com- 
pany are given below, and from these the following is found: 

1750 sq.ft. in 2 sections = 875 sq.ft. per section. Use 3 stacks 
of 19 sections = 91 2 sq.ft. For4| ins. center,area = 3X14.83 =44.5 
sq.ft. 

This is sufficiently close to 41.5 to give little change in velocity. 

For the pipe coils 1450 sq.ft. =4210 lin.ft. 

Each section must contain 1403 lin.ft. Hence use 2-6-ft.-2E 
heater units in each section. The area is 21.2 X2 =42.4, which 
is close enough to give the proper velocity. 

In each of the above cases the area was large and conse- 
quently the velocity would be low. This would reduce the 
heat transmission and require more surface. This is not 
necessary in the cases above. 

The tables give the over-all dimensions of these heaters 
with the allowance for staggering. The Vento heater of 6 stacks 
will require (3X88''-}-5''H-io'0x(2Xio''+4^0 X6o'' = 279'' X 
24^X60'' high. 



184 ELEMENTS OF HEATING AND VENTILATION 

The Buffalo coils, (2X7'-io'0x(3X8i'0X72''- 

To reduce the column headed lineal feet of i-in. pipe in the 
table of the Buffalo Forge coils to square feet, the numbers 
are divided by 2.9. 

In regard to the Vento heater it is to be remembered that the 
makers build a narrow section containing about three-quarters 
of the heating surface of the regular section, but having the 
same dimensions in height and width with the same air space. 

Both forms of heaters are in common use; some designers 
prefer one, some the other. 

To find the number of sections to use in the main heater, 
the number of sections must be found to give the required 
temperature of the hot air and from this the number used in 
the tempering coils must be subtracted. 

Thus at 730 ft. per minute 3 sections of Vento heaters must 
be used to give 98° F., and at 800 ft. per minute 4I sections of 
coils must be used to get this temperature. This latter means 
5 sections. The heating coils will then be made of i section of 
Vento heater or 2 sections of coils. The surface required is 
found as follows: 

From curves, Fig. 90a, for Vento heater: 

3X1340- 2X14 50 

h = = 1120; 

I 

511 ,000 

Area = = 4 So. 

1120 ^^ 

From curves, Fig. 92a, for coils: 

1580X5 -1750X 3 
h= ^ = 1325; 

S 1 1 ,000 

Area = ^^— ^ — =385; 

1325 

907,500 
Area for air passage = —7- = 20. 7 for Vento; 

907.500 . 

= Z — 37" = iQ-o for coils. 
800 X 60 ^ 



INDIRECT HEATING 



185 



For the Vento heater i stack of 28 60 in. sections, 4f -in. centers, 
will be used giving 448 sq.ft. and 21.86 sq.ft. area for air 
passage. For the coil: 

385 sq.ft. = 1120 hn.ft. per section; 

2 sections of 560 lin.ft. per section; 

5-ft. section 3Z) will be used with a | section. 

This gives 567 lin.ft. and 16.8 sq.ft. area. ^ 

SIZES AND DIMENSIONS OF BUFFALO STANDARD FAN SYSTEM 

HEATER 



Length of 
Section. 


Section No. 


Extreme 

Height of 

Heater. 


Width of 

Section. 


Lineal Feet 
of I -inch 
Pipe per 
Section. 


Area for Air 

Passage, 
Square Feet. 


Weight. 


3' 
4 row 


lA 

2A 
3A 
4A 
5A 
6A 


3' A" 

3 10 

4 4 

4 10 

5 4 
5 10 


81" 

8i 

8i 

8* 

8i 

8i 


158 
178 

193 
221 
249 

277 


51 

5-4 
6.1 
6.9 
7-7 
8.5 


423 
454 
477 
520 
564 
607 


4' 
4 row 


iB 
2B 
3B 
4B 


5' A" 

5 10 

6 4 

6 ID 


81" 
8^ 
8^ 
81 


320 
356 
392 
428 


9.8 
10.8 
II. 8 
12.9 


739 
795 
850 
906 


4' 6" 
4 row 


iC 
2C 

3C 

4C 


5' 10" 
6 4 

6 ID 

7 4 


8| 
8i 
81 


396 
436 

477 
516 


12.0 
13.0 
14.0 
150 


881 

943 
1006 
1066 


5' 
4 row 


iD 

2D 

3D 
4D 


6' 4" 

6 ID 

7 4 
7 ID 


8*" 

8* 
81 


479 
523 
567 
611 


14-3 
15-6 
16.8 
17.8 


1046 
1114 
1185 
1251 


6' 
4 row 


lE 

2E 

3E 

4E 


7' 4" 

7 ID 

8 4 
8 10 


81" 
8i 
81 
81 


670 
722 

774 
826 


19.7 
21 .2 
22.7 
24. 2 


1388 
1479 
1549 
1630 


7' 
2 row 


iF 
2F 
3F 

4F 


8' 4" 

8 10 

9 4 
9 10 


6" 
6 
6 
6 


480 
512 
544 
576 


27.0 
29.0 
30.8 
32-5 


1039 
1089 
1138 
1188 



From Catalogue 197, Buffalo Forge System. 



186 



ELEMENTS OF HEATING AND VENTILATION 



VENTO CAST-IRON HOT-BLAST HEATER 

Regular Section, Ratings and Free Areas 

Regular 40" Section, 10.75 square feet. Height 41^". Width 9I' 



No.of|?ro1 
Loops, Qf 

Stack 'Heating 
^^'^^^ Surface. 



75-25 
86.00 
96.7s 
107.50 
118.25 
129.00 
139.75 
150.50 
161.25 
172.00 
182.75 
193.50 
204.25 
215.00 
225.75 
236.50 
247.25 
258.00 



*Equiv- 

alent 

in 

Lin. Ft. 
I -inch 
Pipe. 



226 
258 
290 
323 
355 
387 
419 
452 
484 
516 
548 
S8i 
613 
645 
677 
710 
742 
774 



5" Centers of 
Loops. 



Standard 44% 
of Face. 



Net Air 

Space in 

Square 

Feet. 

4-34 

4-96 

5.58 

6.20 

6.82 

7-44 

8.06 

8.68 

9.30 

9-92 

10.54 

II. 16 

11.78 

12.40 

13.02 

13.64 

14.26 

14.88 



5f" Centers of 
Loops. 



52% of Face. 



+ -ntT-^+v, Net Air 
Inches. ^^^^_ 



35 
40 
45 
50 
55 
60 
65 
70 
75 
80 
85 
90 
95 
100 
105 
no 

115 

120 



5-12 
5.85 
6.57 
7.29 
8.02 

8.74 

9-47 
10. 19 
10.91 
11.64 
12.36 
13.09 
13.82 
14-54 
15.26 
iS-98 
16. 71 
17-43 



t Width 
Stack in 
Inches. 



38 

43 

48 

54 

59 

65 

70 

75 

81 

86 

91 

97 

102 

108 

113 

118 

124 

129 



4f" Centers of 
Loops. 



37% of Face. 



Net Air 

Space in 

Square 

Feet. 



3.67 

4. 20 

4-72 

5-25 

5-77 

6.30 

6.82 

7-35 

7.87 

8.40 

8.92 

9-45 

9.97 

10.50 

II .02 

11-55 

12.07 

12.60 



t Width 
Stack in 
Inches. 



Actual 
Weight 
of Stack 

in 
Pounds. 



32 
37 
42 
46 
51 
55 
60 
65 
69 
74 
79 
83 
88 
92 
97 
102 
106 
III 



594 

670 

728 

851 

936 

1022 

1167 

1 193 

1278 

1364 

1449 

1535 

1620 

1706 

1790 

1876 

i960 

2045 



Ap- 
proxi- 
mate 
W'ght. 






Regular 50" Section, 13.5 square feet. Height 50ff". Width 9J 





5" Centers. 


5I" Centers. 


4I" Centers. 




7 


94-5 


284 


5-37 


35 


6.35 


38 


4-55 


32 


717 




8 


108.0 


324 


6. 14 


40 


7.25 


43 


5-20 


37 


810 


jj 


9 


121. 5 


365 


6.91 


45 


8.15 


48 


5-85 


42 


923 


. M 


10 


135-0 


405 


7.68 


50 


9-05 


54 


6.50 


46 


1026 


05 <U 


II 


148-5 


446 


8.45 


55 


9-95 


59 


7-15 


51 


1129 


-2 ^ 


12 


162.0 


486 


9.22 


60 


10.85 


65 


7.80 


55 


1232 




13 


175-5 


527 


9-99 


65 


11-75 


70 


8.45 


60 


1335 


14 


189.0 


567 


10.76 


70 


12.65 


75 


9. 10 


65 


1436 


•*i a 


15 


202.5 


608 


11.53 


75 


13-55 


81 


9-75 


69 


1539 


^^ 


16 


216.0 


648 


12.30 


80 


14-45 


86 


10.40 


74 


1644 




17 


229.5 


689 


13.07 


85 


15.35 


91 


II .05 


79 


1747 


V +i 


18 


243.0 


729 


13.84 


90 


16.25 


97 


II .70 


83 


1852 




19 


256.5 


770 


14-59 


95 


17-15 


102 


12.35 


88 


1955 


1? 


20 


270.0 


810 


15-36 


100 


18.05 


108 


13.00 


92 


2060 


21 


283.5 


851 


16.13 


105 


18.95 


113 


13.65 


97 


2160 


.s2i 


22 


297.0 


891 


16.90 


no 


19.85 


118 


14.30 


102 


2263 


t-l u5 


23 


310.5 


932 


17-67 


115 


20.75 


124 


14-95 


106 


2370 




24 


324.0 


972 


18.44 


120 


21.65 


129 


15.60 


III 


2470 


o> 



* The actual length of i-inch pipe per square foot of outside surface is 2.9 lineal feet 
but is nominally figured at 3 lineal feet, as shown in the third column of above table, 
t Add to the width of stack 2| inches for staggering ol stacks. 
Taken from American Radiator Co. Catalogue. 



IXDIEECT HEATING 



187 





Regular 6o 


" Section, 16 square feet. 


Height 


60H". 


Width 9 


1". 






5" Centers. 


Sf" Centers. 


4t" Centers. 




7 


112. 


336 


6.45 


35 


7.62 


38 


5-47 


32 


864 




8 


128.0 


384 


7.37 


40 


8.70 


43 


6.25 


37 


988 


-tj 


9 


144.0 


432 


8.29 


45 


9.77 


48 


7-03 


42 


I112 




10 


160.0 


480 


9.21 


50 


10.85 


54 


7.81 


46 


1238 


rt'S 


II 


176.0 


528 


10. 13 


55 


11.93 


59 


8.59 


51 


1362 


3& 


12 


192.0 


576 


1 1. OS 


60 


13.00 


65 


9.37 


55 


i486 


tj M 


13 


208.0 


624 


11.97 


65 


14.08 


70 


10.15 


60 


1610 


a a 


14 


224.0 


672 


12.89 


70 


15.15 


75 


10.93 


65 


1734 


^ 0, 


15 


240.0 


720 


13.81 


75 


16. 23 


81 


II. 71 


69 


1858 


cria 


i6 


256.0 


768 


14-73 


80 


17.31 


86 


12.49 


74 


1982 


WW 


17 


272.0 


816 


15-65 


85 


18.39 


91 


13.27 


79 


2106 


OJ+f 


i8 


288 . 


864 


T6.57 


90 


19-46 


97 


14.05 


83 


2230 


^^ 


19 


304.0 


912 


17-50 


95 


20.54 


102 


14.83 


88 


2352 


i^ 


20 


320.0 


960 


18.42 


100 


21.62 


108 


15.61 


92 


2478 




21 


336.0 


1008 


19-34 


105 


22.70 


113 


16.39 


97 


2600 


tft 


22 


352. 


1056 


20.26 


no 


23.78 


118 


17.17 


102 


2725 


n« 


23 


368.0 


1 104 


21.18 


115 


24.85 


124 


17-95 


106 


2850 


:2 


24 


384-0 


1152 


22. 10 


120 


25-93 


129 


18.73 


III 


2970 


a 



The size of the supply and return for these heaters is found 
by determining the weight of steam condensed and then using 
one of the three methods given in the previous chapter. 

^^r ' ^ r T Heat from heater per hour 

Weisfht of steam per hour = : ; 

t — qo 

i = heat content of the entering steam ; 

go = heat of Hquid at temperature of return. 

The covering around the heaters is usually made of sheet 
iron of about No. i8 or No. 20. This is put together with 
stove bolts so that the apparatus may be taken apart when 
necessary. The casing should lead to the inlet and doors should 
be provided for inspection of all parts. 

The air should be drawn through a wire screen to prevent 
leaves and sticks from entering, or air washers of the forms 
shown in Chapter II may be used. 

The design of the flues and ducts is next considered. 

Flow of Air. There is a loss of pressure due to friction as air 
flows through piping. This loss as in all fluids varies directly 
as the length of piping considered; inversely as the hydraulic 
radius of the pipe, which is the ratio of the area of the pipe to 
its perimeter, and directly as some power of the velocity of the 
air. There are two velocities to be noted. At a low velocity 
the air is found to travel in parallel lines and under these con- 



188 



ELEMENTS OF HEATING AND VENTILATION 



ditions the friction varies as the first power. On increasing the 
velocity beyond that giving parallel flow, the limit of which 
is known as the critical velocity, the air is found to have a 
turbulent passage and friction varies as the square of the velocity. 
As most velocities used are beyond the critical velocity, this 
latter method is the only one to be considered. 

There are several methods of stating the pressure in gases. 
One method is in ounces per square inch, or pounds per square 
inch, above the atmosphere. Another method is in inches or 
feet of water, which means the distance the water will rise in a 
U tube when connected to the system carrying the air on one 
leg while the other leg is connected to the atmosphere. A 
still further method is to express this in feet of the air or gas 
considered. This expression gives the height to which the 
column on one side of a U tube would rise beyond the level in 
the other if the substance were air or gas of constant density 

equal to that of the air at the point, 
and the U tube were connected as 
mentioned above and shown in Fig 
138. Another way in which to ex- 
plain this is to say that the pressure 
or head of so many feet of a sub- 
stance means the height of a column 
of substance one square inch in 
cross-section which would weigh an 
amount equal to the pressure per 
square inch. Thus if h equals the 
feet head of a substance and hi the 
head in inches, w the weight of a 
cubic foot in pounds, W the total weight in pounds, p the 
pressure in pounds per square inch, and po the pressure in 
ounces per square inch, the following equations hold: 



[ 



=^ 



-^-^S^r^^^^^^^^;^^^^^:^^:^^^^^^^^ 



] 



^^^^^^^^^^^^^^^^r^r^^^^r^r^^ 



Fig. 138.— U Tube. 



h = 



144P 



W 

hi=i2h 



po 
"^^gPo 

w 



w 



(88) 

(89) 



INDIRECT HEATING 189 

For water 2^^ = 62.5 lbs. 

h = 2.^op = o.i^/[po (90) 

hi = 2'j.6op = i.'j2Spo (91) 



For air or gas 



i4#Xi • , . 



where _^ = pressure in pounds per square inch. 

^ = 53-34 for air (93) 

^_ £544 . . 

mol. density for any gas * * * ^^^y 

r = absolute temperature in degrees F. 

The pressure p is the total pressure on the air and is equal to 
the barometric pressure plus that above the atmosphere. 
In general for air at atmospheric pressure and 70° F. 

w = —77 -7-, x= 0.0748= lbs. . . (gO 

53-34X (459-6 + 70) '^ 13-3 

Hence 

^^lr = -^^:^ = ^20 po= 1920 P . . . (96) 
/Zx air = 1440 i^o (97) 

The relation between inches of water and inches of air at 
70° and atmospheric pressure is given by 

hiw hi air /^air / ^x 

^° = I7^8 = i^o = ^- (98) 

or 

120 hi^ 

^alr= j_^28 "^^-^ ^'^ ^99^ 

/^i air = 69.5X12 hi^ 

= ^35'Ohi^ (100) 



190 



ELEMENTS OF HEATING AND VENTILATION 



The subscripts, ^' air " and " u'/' refer respectively to head 
in feet or inches of air or water. 

If a set of tubes is placed in the side of a pipe line carrying 
air or other gas, these heads or heights represent the distances 



[ 



] 



Fig. 139. — Loss in Head. 

to which the air would rise if of uniform density due to the 
pressure of the pipe. If now there were two of these tubes, 
known as piezometers, placed at two points on a line as shown 
in Fig. 139, the . difference in level would show the loss in 
pressure due to friction. The question of correctly measuring 



^ 



Fig. 140. — Piezometers. 

the static pressure in a line carrying gas with some velocity is 
of importance. The best manner is to have a tube attached 
to the wall of the pipe absolutely perpendicular and finished 
flush with the surface as shown in Fig. A, 140, or a tube may be 
introduced as shown in the figure on which is a large, normal 
disc with sharp edges. The purpose of the disc is to cut out 



INDIRECT HEATING 



191 



eddies which form around any tube and give incorrect readings. 
Aspiration effect is usually produced by the tube entering as 
at C, Fig. 140, although there may be an increase of pressure 
due to impact of the air. The introduction of a tube as at D, 
Fig. 140, will give a pressure reading equal to the sum of the 
static pressure and the pressure due to velocity and for that 
reason it is sometimes called the dynamic pressure. The dif- 
ference between the dynamic pressure and the static pressure is 
the velocity pressure or the Pitot pressure. A Pitot tube is a 
tube bent in the direction of the flow connected through a U 




Fig. 141.— Pitot Tube. 



tube to a static pressure tube, Fig. 141. In this way the pres- 
sure in inches of water due to the velocity may be found. Exper- 
iment and theory indicate that if this pressure be reduced to 
feet of the substance carried in the pipe the velocity is given 
by the equation 

^2 

^alr=^2^/Zair Or hlT = f^ .... (lOl) 

/Zair = feet of air equal to difference in pressure between 

the static and dynamic pressure; 
^air = velocity of air in feet per second; 
^ = 32.174 acceleration of gravity; 



192 



ELEMENTS OF HEATING AND VENTILATION 



Since 



ha,ir = ^9-5 hw (for 70° and atmospheric pressure) 



V2gX6g.shiu; = 66.gVhi^ (102) 



These two tubes are sometimes combined in one as shown 
in Fig. 142, but such a tube is apt to give incorrect read- 
ings because the static tube is subject to 
eddy currents. The objection to the single 
static tube at the wall is that the pressure 
may not be thought to be constant over 
the section of the flue, but experiment 
seems to indicate that the pressure is uni- 
form. 

The loss in pressure due to friction 
may now be discussed. The usual method 
is to express the loss in feet of head of the 
fluid being carried. Experiment then gives 
(beyond the critical velocity) : 



Fig. 142. — Arrangement 
of Pitot Tube with 
Static and Dynamic 
Tube Together. 



r 






(103) 



(104) 



(^=area in square feet, _/>= perimeter in feet); 
/ = length in feet. 

Before reducing this it is well to note that since velocity pressure 
head is given by 



h = 



2r 



it is well to introduce 2g into the expression above for con- 
venience and then reducing by use of the other quantities, the 
value of hf becomes for round pipes, 



A 2g 



■=r-^ -=f 



I V^ 



2g 



(105) 



INDIRECT HEATING 193 

For square pipes the same expression holds, while for rectan- 
gular pipes of height d and breadth 2d the expression for r 
becomes 

6d 



r=-:~=id. 



In this case f for such a pipe becomes 

i/and^/=f/^— (106) 

The above discussions really apply to all fluids up to this 
point. In considering the problem of the flow of air, however, 
it must be remembered that the velocity V will vary along a 
pipe line, since the pressure falls and the volume increases as 
the air passes along the pipe line. Hence the above expression 
is only true for a differential length of pipe giving 

"^^^^i'd^^^^'^^^ ..... (107) 
The — sign is used because h falls as / increases. 

_MRrjKd^ 

^~ i4# * 4 



now 



If = pounds of air per second; 
,, 144^^ RT , 

RT 

p 1/ MRT ydl , 
-^^ = Wd[ iJ2 2~ .... (109) 

fM^RT dl 



194 ELEMENTS OF HEATING AND VENTILATION 

If T is assumed constant this integrates into 
pi^-p2^ fM^RT L 

2 ~{ii2,yd^2g • • • • 

pi = the pressure at entrance in pounds per square foot; 
p2 = the pressure at exit in pounds per square foot; 
M = pounds of air per second; 
r = absolute temperature of gas; 

R = gas constant = ■ ' 



(in) 



mol. density' 

Z = length in feet; 
J = diameter in feet; 

The above becomes 



(^-^2)— ^— =/(^^^- . . . (1 1 2) 



2 
p\-\-p2 

= mean pressure. 

pi — p2 = drop in pressure. 
Hence 

Drop in pressure in pounds per square inch 

M^RT L 

where pm is mean pressure. 

If pi—p2 is reduced to feet of air at mean pressure this 
formula reduces to 

Drop in feet of gas at density of mean pressure 

= h — (114) 

This is the same expression as that used for liquids where the 
specific volume does not change for a considerable change in 
pressure. In the case of air under pressure there may be a 



INDIRECT HEATING 195 

considerable drop and only Eq. (in) or (113) may be used, but 
in cases where there is Kttle change in pressure Eq. (114) may 
be used. This is the same as assuming that there is no change 
in velocity. Then 

^=/i^ • • • ("5) 

The values of / vary with the velocity and the diameter of 
the pipe. According to Weisbach the constant is 0.0193 when 
h is in feet of gas, as / and d are in feet and V, is in feet per second. 



0.0172 
Weisbach proposes /= 0.0144 + ^-:=^. . . (116) 



Arson proposes/ =0.03+-^ — (117) 

0.005 
Darcy proposes the formula 0.016 + — ^ — . . (118) 



and sometimes he gives this form 



bee . . 



The Green Economizer Company gives values which reduce 
this to 

0.0274 0.0014s 0.0120 , . 



These formula give curves shown in Fig. 143, from which the 
average value is 0.02. For brick or concrete/ is increased about 
50 per cent. Formula 115 may be used for the flow of air in 
heating systems, since there is little change in the pressure. 

The loss in pressure due to bends in pipe lines carrying fluids 
is usually expressed as 

hi = K— (121) 

2g 



196 ELEME^'TS OF HEATI^TG A>:D VENTILATION 

Where K is an experimental constant ; 

Ai = loss in feet of head; 

z; = velocity in feet per second; 

The loss due to obstruction of various kinds, such as valves, 
grills or branches is given by the same kind of an expression. 



0.060- 



0.055- 



0.050- 



0.045 



0.040 



0.035- 



0.030 



0.025 



0.020 

0.015- 

0.010- 



10 























































































































































\ 




























\i 


V 


























1 


\ 


























\ 


^v 


\ 


^ 


^^^^^ 


d 


^H— 


















^ 


^^==^ft*. 


:^ 


^ 


^=^ 


■fj= 


__3[eisb 

1 •■ 


achls_Fo_rmula__ 
















" 


'=^P 1 1 1 









20 30 40 50 

Velocity in Feet per Sec. 



Fig. 143. — Values of /by .\rson, Weisbach & Green Economizer Co. 



The values of K used, as given by the Green Fuel Economizer 
Company are: 

0.3 for sharp bends; 

0.25 for bends with R = d; 

0.15 for bends with R = 2 to ^d\ 

0.07 for bends wdth i? = 5 to 6J; 

0.00 for bends with R>6d; 

0.15 for branches at 135°; 

1.5 for grill or register, free area = | total area = area of flue; 

0.75 for grill, free area= ij area flue. 



INDIRECT HEATIXG 197 

At times the expression for the loss in bends is given as 

''»=/-rfig ^^") 

In which / is given as the length of an equivalent pipe. Since 
this expression is similar to the expression for the loss due to 
friction of straight pipe, one expression may be used for both 
if / represents the length of pipe plus the equivalent length of 
the bends. 

N. S. Thompson gives the following equivalent lengths of 
bends in terms of the diameter or widths. 



: Quarter Bend. 


Equivalent Length. 


qD 


looD 


ID 


6sD 


\D 


30Z) 


iD 


loD 


ihD 


6D 


2D 


SD 



For sudden enlargement, if there is little change in pressure the 
expression for loss is 

Where vi is the velocity before enlargement while V2 is the velocity 
after enlargement. For contraction the velocities refer to that 
in vena contracta after the contraction and that in the small 
pipe. These are difficult to find and this loss is, moreover, very 
small. The main loss is in enlargement and this with that 
due to contraction may be eliminated by gradual changes in 
section. From the above it is seen that the total head causing 
flow up to a given point is 

/ v^ v'^ "o"- z;2 

^ d2g 2g 2g 2g 



198 ELEMENTS OF HEATING AND VENTILATION 

The first term is due to friction, the second to a bend, the third 
to a grill or branch and the last to the velocity. If there is httle 
change in temperature and pressure the following is true approx- 
imately: 

Q = nAi=V2A2=v^Az (125) 

Q = quantity per second in cubic feet; 
vi, V2, '^3 = velocities at various sections in feet per second; 
Ai, A2, ^3 = areas at various sections in square feet. 

Since the volume of a gas depends on absolute pressure and 
temperature the change from 120° F, to 110° F. would mean 
a change in the volume and hence in the velocity of 



459.6 + iio _569.6_ ^ 
459.6 + 120 579.6 '^ ^ 



or a difference of less than 2 per cent; while a change in pres- 
sure of 2 ins. of water to o in. would mean a change of 

408 + 1 _ 409 

408 + 2 ~4^""^^^ 

or about J per cent. 

It is seen then that in most problems of indirect heating 
the pressure and temperature changes are so shght that for- 
mulae used for Hquids may be employed and hence the velocity 
of any particular section may be expressed in terms of any 
other section of different size provided the quantity is the same. 
In most air pipes, however, the section is only changed when the 
quantity is changed. Hence in working out the total loss in 
any system the total loss may be written 

di 2g 2g 2g 

In this the various losses are worked out for their different 
velocities and the — is the final velocity head. In this work 

2g 



INDIRECT HEATING 199 

the sections change so gradually that there is no loss at such 
points. 

The principal factor of the expression is that due to friction 
on the side walls or 

d 2g' 



since 



MRT K'M , 

V = — -j^ = ~w~ lor ^^y given condition , 



n = K"^f (..7) 

or 

M=K"'-~ (128) 



This shows that the head loss varies directly as the length and 
square of the mass and inversely as the fifth power of the diameter, 
or the mass handled varies directly as the | power of the head, 
the I power of the diameter and inversely as the J power of the 
length. These two statements are important, as will be seen 
in laying out a system. For instance if the length of piping is 
the same, and the quantity is the same the diameter of two 

pipes will have to be to each other as ( — -] if there is 50 per 

cent more drop in the first than in the second. If the drop and 
length are the same but the quantities are as 2 : i then the 
diameter will be as (2)^ : i. These same statements as to diam- 
eter may be made of pipes of any form if they are geometrically 
similar. Thus if rectangular pipes are always made with a 
given ratio between the two dimensions and the smaller one is 
called d the expression 

^/=X'''-^ IS true, 



200 



ELEMENTS OF HEATING AND VENTILATION 

1.00 



0.80 



O.60 



20.40 



0.20 





















/ 






0. ^ 




y 










/ 


















/ 


/ 


















/ 


















/ 


/ 


















/ 


















/ 


















/ 


/ 
















y" 


/ 














^ 


^ 















0.20 0.40 



Values of 



0.80 1.00 



Fig. 144. — Variation of — for Different Values of — for Same Friction Loss 

and Same Length. 



1.00 


















^ 


y 


n sn 














y' 




















/^ 


y^ 








,0.60 








/ 


y 
















/ 


/ 
















^0.40 

> 




/ 


v 


















/ 


















0.20 


/ 




















/ 






















L 





















0.20 



0.40 0.60 

Values olJl 
h 



0.80 



1.00 



Fig. 145.— Variation of -— with Different Values of — for Same Friction Loss 
and Same Diameter. 



INDIRECT HEATING 



201 



Fig. 144, which gives ^ plotted as (j^Y, Fig. 145 with ^, 



62' 



as 



1.00 



0.60 



•K 



5 0.40 



0.30 





















\ 




















/ 








d2'' 












/ 






h2 ( 


d2^ 












/ 


















1 








































1 


















/ 


















/ 


/ 

















^ 


^ 









0.40 
Values of 



o.e 



1.00 



Fig. 146.— Variation of -} with Different Values of - for Same Friction Loss 

and Quantity. (This curve may be used for -^ for different values of - for 

hi d2 

same length and quantity.) 




Values of r * 

Fig. 147.— Diagram for Discharge from Pipe. 

[jj\ and Fig. 146, with i^£\ plotted as UY are of value i 
working out problems of relative duct sizes. 



202 



ELEMENTS OF HEATING AND VENTILATION 



The further use of this will be explained later. 

It may be necessary to measure the quantity of air flowing 
and to do this there are five general methods: first the Pitot 
tube, second a standard orifice, third an anemometer, fourth a 
Venturi meter and fifth an electric meter. 

The Pitot tube has been described. By means of this instru- 
ment the velocities at different points in the pipe are found and 
if these velocities are supposed to remain constant around any 
given radius the following expression will give the quantity Q : 



Q= )v2'7:rdr 
= 'Kfvd{r^) 



(129) 




C 
Fig. 148. — Orifices. 



D 



Hence if the values of v be plotted as ordinates against the 
values of r^ of the points as abscissae the area of the curve, 
Fig. 147, when multiplied by x will give the value of Q. In 
measuring Q in this way more readings should be taken near the 
edge of the pipe than near the center. 

In the second method, that of the standard orifice. Fig. 148, 
the velocity is determined by the thermodynamic equation: 



vel. = \^{ii-i2) =\^g-jzr^{Pin-p2V: 

vel.=vel. in feet per second; 
i = heat content in B.t.u.; 



Now 
Hence 



INDIRECT HEATING 203 

^= pressure in pounds per square foot* 
z; = voL of I lb. in cubic feet; 

^ = — = 1 .40 = ratio of specific heats ; 



vel. = V.,^-^^..[x-(g)-]. . . (130) 

The quantity discharged in pounds per second is given by 
(2 = aXvel.; 

M = ^ = '-^; 

V2 ^2. 

where 

a = area of orifice ; 



=4«j^)*(s)*[©--(r]' • • <-' 

When p2 = o.^2Sp the maximum discharge occurs. 

FHegner found by experiment that ^2 =0.5767^1 at the point 
of maximum discharge, and this as well as the theoretic value 
for maximum discharge reduces Eq. (131) to 

M = o.S3oa^^, (132) 

where 

M = pounds per second ; 
a = area in square inches ; 
pi = pounds per square inch of high pressure 
ri= absolute temperature. 



204 



ELEMENTS OF HEATING AND VENTILATION 



The weight for any pressure p2<o.^pi is the same as above, 
so that so long as the pressure p2 is below its critical value the 
discharge in pounds is a fixed quantity and independent of p2. 
Above this critical value the discharge does depend on p2.. 

FKegner gives this equation in the form, 



M = i.o6oa 



4 



p2(pl-p2) 



Ti 



(133) 



This equation is for a rounded orifice. For a sharp-edged 
orifice in a thin plate a constant of 0.62 is used, by which to 
multiply the theoretic discharge. The constant is about 0.83 
for short tubes and 0.92 when these are rounded at entrance. 

The anemometer, Fig. 149, is only of value when the velocity 
is not over 1200 to 1500 ft. per minute and hence it is used often 

in heating work where these 
velocities are found. The in- 
strument is checked by re- 
volving it on a long arm and 
noting the distance moved and 
that recorded. In this way 
the instrument is calibrated. 
In using this apparatus the 
readings may be plotted as 
velocities on a diagram similar 
to that used with the Pitot 
tube or the area of a pipe 
or duct may be divided into 
square areas by imaginary lines and the velocity determined in 
each of them. The average of ^ these will give the average 
velocity. Another method is to gradually move the anemometer 
over the area of the duct or pipe covering the whole pipe in this 
way and the recorded amount per minute will give the average 
velocity. 

The Venturi meter, Fig. 150, consists of a converging and 
diverging section of pipe. The diverging section is more grad- 
ual on account of the loss due to enlargement being greater 
than that due to contraction. 




Fig. 149. — Anemometer. 



INDIRECT HEATING 



205 



By equating the sum of the energies at the large and small 
sections and remembering that the expansion is adiabatic the 
formula for the discharge may be derived. Thus: 



k-i 



\-piVi 



vel.i^ P2V2 



2g 
ai vel. 1 a2 vel.2 






Vl V2 



k , , vel. 

j—^{pin-p2V2)= — 



'm-'\ 



vel.i= hg- 



-piVi 



I — 



Ia2\p2/^ J 



M = 



ai vel.i 



Fig. 150. — Venturi Meter. 



(134) 



(135) 




pi = pressure in pounds per square foot at section i; 
^2= pressure in pounds per square foot at section 2; 
1)1 = specific volume in cubic feet; 
2^2 = specific volume in cubic feet; 

^ = ratio of specific heats; 
vel. 1 = velocity in feet per second; 

a = area in square feet; 

g = acceleration of gravity; 
ili' = mass per second. 



206 ELEMENTS OF HEATING AND VENTILATION 

The methods thus used are apphcable under different con- 
ditions. The anemometer is appHcable to low velocities up to 
1500 ft. per minute, the Pi tot tube to velocities of 2400 to 7000 
ft. per minute, and the standard orifice to higher velocities when 
the pressure drop is considerable. The Venturi meter is applic- 
able to steady flow of all velocities. 

A recent method used by Prof. C. Thomas consists in 
heating gas by a known amount of electrical energy and then 
by the rise in temperature finding the mass of gas, and from 
it the volume and thus the velocitv. 



Volts X amp. 42.42 

746 ^^^.=M .... (136) 



.239(^2 -/i) 

If = mass of air per second; 
volts = average voltage ; 
amp. = average current; 

/2 = temperature of outlet; 

/i = temperature of inlet; 



, MRT 

vol. = — ; 

i4# 



vol. - . 

= velocity. 

area -^ 



If the head lost is h ft. of air the work required to overcome 
this per second if Q cu.ft. per second are discharged and each 
cubic foot weighs w lbs. is 

work per second = whQ = prp hQ . . . (137) 






INDIRECT HEATING 207 

The formulae may now be appKed for the following tables: 

TABLES TO BE USED IN DESIGN WORK 

Pressures and Velocities of Air at 70° F, 



Inches 


Ounces 


Velocity, 


Inches 


Ounces 


Velocity, 


Inches 


Ounces 


Velocity 


Water. 


Pressure. 


Feet per 
Second. 


Water. 


Pressure. 


Feet per 
Second. 


Water. 


Pressure. 


Feet per 
Second. 


^ 


0.04 


16.7 


^ 


0.25 


44.2 


if 


I .01 


89 


i 


0.07 


23.6 


2 


0.29 


47 


3 


2 


1. 16 


95 


^ 


O.II 


28.9 


1 


0.36 


52 


8 


3 


1-73 


116 


i 


0.14 


33-4 


3 
4 


0.43 


57 


9 


4 


2.31 


134 


A 


0.18 


37-3 


7 

8 


0.51 


60 


7 


6 


3-47 


167 


1 


0.22 


40.9 


I 


0.58 


66 


9 


8 


4-63 


189 








li 


0.72 


74 


9 


12 


6.94 


232 








li 


0.87 


82 





16 


9-25 


368 



Diameter of Pipes for Various Capacities and Velocities 



Cubic 






















Feet of 
Air per 


500 


600 


700 


850 


1000 


1200 


1400 


1700 


2000 


2500 


Minute. 






















200 


8.6 


7.83 


7.2 


6.6 


6.0 


5-5 


5-1 


4-7 


4-3 


3-9 


400 


12.2 


II .1 


10.3 


9-3 


8.6 


7 


8 


7.3 


6.6 


6.1 


5-5 


700 


16.0 


151 


13-6 


12.3 


II-3 


10 


4 


9.6 


8.8 


8.1 


7.2 


1000 


193 


17.5 


16.2 


14.8 


13-5 


12 


4 


II-5 


10.5 


9.6 


8.6 


1500 


23-5 


21.4 


19.9 


18.0 


16.6 


15 


2 


14. 1 


12.8 


II. 8 


10.5 


2000 


27.1 


24.7 


22.9 


20.8 


19.2 


17 


9 


16.2 


14.8 


13-6 


12.2 


3000 


33-2 


30.3 


28.0 


25-5 


23-5 


21 


4 


19.9 


18. 1 


16.7 


14.9 


4000 


39-3 


35-0 


32.4 


29.4 


27.1 


24 


7 


23.0 


20.8 


19.2 


17.2 


5000 


42.8 


39-2 


36.3 


32.9 


30.3 


27 


8 


25-5 


23-3 


21-5 


19.2 


7500 


52.5 


47-9 


44-3 


40.2 


35.8 


34 





31-5 


28.7 


26.3 


23-5 


1 0000 


61.0 


55-3 


51-2 


46.6 


42.8 


39 


2 


36.3 


32.9 


30-4 


27.2 


15000 


74.2 


67.8 


62.9 


57-0 


52. 5 


47 


9 


43-9 


40.3 


37-1 


3S-2 


20000 


85.6 


78.3 


72.3 


65-7 


60.0 


55 


4 


51.2 


46.4 


42.9 


38.4 


30000 


105.0 


95-8 


88.6 


80.5 


74.2 


67 


7 


62.7 


57-0 


52.6 


47.0 


40000 


121. 


III.O 


103.0 


92.9 


86.0 


78 


I 


72.3 


65.7 


60.6 


54-2 


50000 


1350 


124.0 


115. 


105.0 


95-8 


87 


8 


81.3 


73-6 


68.0 


60.7 


62500 


150.0 


138.0 


129.0 


115. 


107.0 


98 





91.0 


82.3 


75-9 


67.8 


75000 


166.0 


151. 


140.0 


127.0 


117. 


108 





100. 


90.2 


83.0 


74.2 


I 00000 


193.0 


I75-0 


162.0 


148.0 


1350 


124 





115. 


105.0 


96.0 


85.8 



208 



ELEMENTS OF HEATING AND VENTILATION 



Diameters of 
Circular Areas Equivalent to Rectangular Ducts in Carrying Capacity 



Length 


Width. 


3 


U 


6 


9 


12 


15 


18 


21 


24 


30 


36 


.3 
4 
6 

9 

12 

15 
i8 

21 
24 
30 
36 


3 
3 
4 
5 
6 

7 
7 
8 
8 

9 
10 


7 
9 
6 
6 

3 

6 
I 
5 
4 
I 


4 
5 
6 

7 
8 
8 

9 

10 
II 
II 


4 
4 
6 

4 
3 
9 
5 

I 
9 


6.7 
8.1 
9.2 
10.3 
II .2 
12.0 
12.7 
14.0 
15.2 


10. 

II-5 
12.7 

139 
150 
15.8 
17-5 

19. 1 


13-3 
14.7 
16.2 
17-5 
18.4 
20.5 
22.2 


16.5 
18. 1 

19 -5 
20.8 
23.1 
25.2 


19.7 
20.4 
22.9 

25-5 
27.8 


23.6 

24.7 
27.6 
30.0 


26.4 
29-5 
32.3 


33-0 
36.4 


39-9 



The loss in inches of water in 100 ft. of 12-in. pipe at various 
velocities is given in the table below as well as the horse-power. 

To use this table for any other diameter or length the values 
are multiplied by one one-hundredths of the length and divided 
by one-twelfth of the diameter for loss of head, while for horse- 
powers the tabular values are multiplied by the two factors. 
Thus for 2000 ft. per minute in 75 ft. of 8-in. pipe 

^,=0.51X^X^=0.57 in. 

H.P. = 0.1269 X^^X— =0.0634. 

^ 100 12 ^^ 



FRICTION LOSS AND H.P. PER 100 FEET OF 12-INCH PIPE 



Velocity. 


Friction, 
Inches, Water. 


H.P. 


Velocity. 


Friction, 
Inches, Water. 


H.P. 


200 
400 
600 
800 
1000 


0.005 
0.021 
0.046 
0.082 
0.128 


. 0002 

O.OOII 

0.0035 

0.0082 
0.0159 


1200 
1500 
2000 
3000 
4000 


0.184 
0.288 
0.510 
I . 150 
2.050 


0.0270 
0.0536 
0.1269 
0.4284 
I 0153 



This table for friction loss holds for 12-in. square pipe. 
To show the effect of temperature on the various quantities 
the following table is given: 



INDIRECT HEATING 209 

EFFECT OF TEMPERATURE ON AIR PROBLEMS 





Relative 


P.elative 


Relative 


Relative 


Relative 


Relative 


Tempera- 


Pressure for 


Velocity for 


Weight for 


Volume for 


Power for 


Power for 


ture, 


Same Head 


Same 


Same 


Same 


Same 


Same 


Degrees F. 


of Air. 


Ounce 
Pressure. 


Volume. 


Weight. 


Velocity. 


Weight. 


20 


1. 10 


0.95 


1. 10 


0.91 


I .10 


0.83 


30 


1.08 





96 


1.08 





93 


1.08 


0.87 


40 


1.06 





97 


1.06 





94 


1.06 


0.89 


50 


1.04 





98 


I .04 





96 


I .04 


0.92 


60 


1.02 





99 


1.02 





98 


I .02 


0.96 


70 


I .00 




00 


1. 00 




00 


I. 00 


1. 00 


80 


0.98 




01 


0.98 




02 


0.98 


1.04 


90 


0.96 




02 


0.96 




04 


0.96 


1.08 


100 


0.95 




03 


0.95 




05 


0-95 


1. 10 


IIO 


0-93 




04 


0-93 




07 


0.93 


1. 14 


120 


0.92 




05 


0.92 




09 


0.92 


1. 18 


130 


0.90 




06 


0.90 




II 


0.90 


1.23 


140 


0.88 




06 


0.88 




13 


0.88 


1.28 


150 


0.87 




07 


0.87 




15 


0.87 


1.32 


200 


0.80 




II 


0.80 




25 


0.80 


1.56 


250 


0.75 




16 


0.75 




33 


0.75 


1.78 


400 


0.62 




27 


0.62 




61 


0.62 


2.60 


600 


0.50 




41 


0.50 


2 


00 


0.50 


4.00 



The data for the losses in pipes being known it now becomes 
necessary to outhne the method of procedure for a given plant. 

Register Faces. The register faces should be large enough 
to give a velocity of 300 to 550 ft. per minute when in the wall, 
while 200 to 250 is the value to be used for floor registers. These 
must be selected so that there is no annoyance to the occupants 
of the room. The net area of the register is usually 66 per cent 
of the area of the opening in the end of the duct while there is 
a border of about 2 ins. around this. A 10 by 10 opening 
would give a net register area of 66 sq.in. and would have an 
extreme register face area of about 144 sq.in. 

As a guide the following table of velocities has been com- 
puted from data given in Loomis' Meteorology by Carpenter: 



Just perceptible 
Gently pleasant 
Pleasant brisk 
Very brisk 



175 ft. per minute. 

330 " " 
iioo '' 
2200 " 



210 ELEMENTS OF HEATING AND VENTILATION 

High wind 3100 ft. per minute. 

Very high wind 4000 " " 
Strong gale 5000 " ' ^ 

Flues and Ducts. After the registers the flues may be chosen 
with velocities of 500 to 750 and finally the horizontal flues with 
800 to 1200 ft. per minute. In any case low velocities are of 
value, as the loss depends on the square of the velocity, and the 
only limit is the cost of the ducts and the space available for 
them. Of course for lack of space it may be necessary to increase 
the velocities. The high velocities are limited by noise. The 
values given above will give a quiet system. 

To get the size of the ducts it is well to lay out the system 
as shown in Figs. 136, 137, assuming the velocities to one of 
the rooms, usually the most remote, and from that work out 
the other circuits. 

In Fig. 136 a double-duct system is assumed in which one- 
half of the air is hot and one-half tempered. Assuming the 
velocity in the various parts of the system to room 18, above 
room 12, the pressures are found at the various points. These 
calculations are now given. 

Pressure in rooms = hit); 
Velocity at register = 300 ft. per min. = 5 ft. per sec. 

88000 
Area register = ^^-^^ = 4.9 sq.ft.; 

25 
Velocity head = 7 — = 0.4 ft. air = 0.005 in. water ; 

Velocity in flue = 600 ; 

88000 
Area of flue = 2 — —t~ = 2.4 sq.ft.: 
600X60 ^ 



Loss in brick flue with 2 bends = I 2X0. 2 5+— )i.8 



0.02 X38\ ^ lo^ 



1-5 / ■ 64.3 



(•5 + -5)z — = 2.8 ft. of air = 0.04 in. water. 



INDIRECT HEATING 211 

Velocity in ducts 1200 ft. per minute. 

I 5 1000 

Area of tempered ducts from A to B= — — = 2.1 sq.ft.; 

^ 1200X60 ^ 

(assuming 50,000 cu.ft. per room) 

302000 

From 5 to C = —^ = 4.2 sq.ft. 

1200X00 



004000 
From C to heater — — .- = 12.6 sqit. 
1200X00 ^ 

Area of hot ducts at 98° F. 

From ^ to 5 = 2.1X1.05 =2.2. 
From 5 to C = 4.2X1. 05 =4.4. 
From C to heater =12.6X1.05 = 13.2. 

Losses : 

Tempered A to B [12 X24'']. 

22 20^ 

(0.02X +3X0.25)7 — =12' of air. 

0.33 ^ ^'64.3 

Tempered 5 to C [i2X48'1. 

32\ 20^ , . . 

0.02 X — 7 — =10 of air. 
0.4/64.3 

Tempered C to fan [30X63'']. 

28 , 202 ^ , , . 

(0.02 X— ^+2X0.25)7 — = 8.5 of air. 
0.85 ^'64.3 ^ 

The pressure heads for the hot air in feet of air will be the 
same, although when reduced to oz. pressure they will amount 
to 4 per cent less on account of the higher temperature of air. 
This decrease will be used, however, in the heating coils over 
which the hot air will flow so that the resistance is the same in 
each duct. 

The flues now leading from A to second floor and from A 



212 ELEMENTS OF HEATING AND VENTILATION 

to first floor have to be so designed that they will give the proper 
discharge, for although there is the same drop in each of them 
the lengths are different and hence to get the proper quantity^ 
the area of the flues leading to the lower floors is smaller. The 
quantities are the same for this same drop, hence 

L U 

^'-^\l) -^nsS + ioXilJ ' 
A = 1.32. 

(ij is assumed as Di in getting the equivalent length for the 
quarter bends.) 

38 + ioXii 



2^2 = l2 



Z>2 = 1.26. 

To get the size of the flues at C it must be remembered that 
the quantity is the same as before, but the pressure drop is 
greater since the pressure in the rooms is the same while the 
pressures at the bases of the flues are different. 

h for flues at ^ = 2.8 iL a^l; 
h for flues at C= 2.8 + 12 + 10 = 24.8 ft. air. 



INDIRECT HEATING 



213 



To aid in problems of this kind Figs. 144-146 have been added, 
giving the ratios of Qs, h, ds. 




Fig. 151. — Double Dust Dampers. 



■frrrr 



I!' 



--S 



-^f^=n 



"tiii 



^ 



y 




\ 1 • \ 


-| r--t--n 




— \''~:!A.\ 






V y^-^yrA 


I ' J 




Sot Air \ yy^l 


/ 


-> -^ 


y >^] 


> 







Tempered 
Air 



Fig. 152. — Single Duct System. 



In many cases the flues are all made of the same size and in 
addition to the mixing damper A, shown in Fig. 151, there are 
a pair of dampers, B, shown in the figure, which may be locked 



214 



ELEMENTS OF HEATING AND VENTILATION 



in any position, thus checking the flow in any room and equaliz- 
ing the discharge. 

If the job is equipped with single ducts, as shown in Fig. 
153, then one duct is computed, for instance that to room 18, 
with a velocity of 840 ft. per minute, and then since the pressure 




1.8 .12: 



Fig. 153. — Single Ducts for School No. 3. 



drop to each room is the same with practically the same quantity^ 
the sizes of others are given by 



D, = D 



-L>x\ 5 



L ' 



Now the size of duct to room 18 is 

88200 
Area = 5 — —-7- = 1.7; 
840X60 " 

Loss = 0.02 X 
For room 1 2 



(46+30X1 !) ^ o.03X(38 + 25) 
•3 -3 



J6^ = 35 of am 



h _o. o2(48+38) +0.03(38 + 25) 
hj 0.02(46+38) +0.03(25 + 25)' 



Using this the size of flue and duct are found. Fig. 152 
shows the mixing dampers used in the single-duct method with 
the control damper for discharge. 

Loss of Pressure in Heaters. The losses in the various 
heaters have been found by the manufacturers and some are 
given in the tables below : 



INDIRECT HEATING 



215 



LOSS IN PRESSURE IN BUFFALO HEATERS 



Velocity through Clear 
Area in Feet per Minute. 


Loss in Ounces per Square 
Inch per Section of 4 Rows. 


Loss in Inches of Water per 
Section of 4 Rows. 


700 


0.027 


0.047 


800 


0.035 


0.061 


900 


0.045 


0.078 


1000 


0.055 


0.095 


HOC 


0.067 


0. 116 


1200 


0.080 


0.138 


1300 


0.093 


0.162 


1400 


0.104 


0.180 


1500 


0.127 


0. 220 



The pressure-loss in heaters should not excqed one-half 
total loss in head. 



LOSS IN PRESSURE IN GREEN POSITIVFLO HEATERS WITH 
PIPES ON 2f" CENTERS 



Air 


Loss in Inches of Water. 


Velocity in 
Feet per 
Minute. 


4 Rows. 


8 Rows. 


12 Rows. 


16 Rows. 


20 Rows. 


24 Rows. 


600 


0.04 


0.06 


0.09 


0.12 


0.14 


0.15 


800 


0.06 


O.IO 


0.15 


0.19 


0.23 


0.26 


1000 


0.09 


0.15 


0.23 


0.30 


0.37 


0.41 


1200 


0.12 


0.21 


0.31 


0.43 


0.50 


0.58 


1400 


0.17 


0.30 


0.45 


0.60 


0.75 


0.90 


1600 


0.20 


0.34 


0.52 


0.69 


0.86 


1.03 



Free air space = 



Lineal feet of pipe 



L4Xrows of pipe 
LOSS IN PRESSURE IN VENTO HEATERS IN INCHES OF WATER 



Velocity 

through Clear 

Area in Feet 

per Minute. 


I Section. 


2 Section. 


3 Section. 


n Sections. 


400 
600 
800 
1000 
1200 
1400 
1600 


0.015 
0.033 
0.059 
0.092 

0.133 
0.180 
0.236 


0.018 
0.041 
0.072 
0. 112 
0.162 
0.220 
0.288 


0.018 
0.058 
0. 104 
0.162 
0.234 
0.318 
0.416 


o.oi8+o.oo8(« — 2) 
o.04i+o.oi75(« — 2) 
0.072+0.032(^-2) 
0. 112+0.050(^-2) 
0. 162+0.072(^ — 2) 

0.220 + 0.098(« — 2) 
0. 288 + 0. I28(«-2) 



216 



ELEMENTS OF HEATING AND VENTILATION 



Fans. There are several forms of fans used for mechanical 
ventilation. The plate fan used for many years consists of a 
wheel with a number of radial paddles or vanes, Fig. 154 ^, or a 
number of curved vanes, Fig. 154 B, enclosed in a metal casing. 
These were used for many years and in 1897 Mr. S. C. Davidson 
of Belfast, Ireland, invented a curved vane wheel in which the 




Fig. 154. — Radial Vanes on Standard Form of Fan. 

Wheel. 



Curved Vanes on I-Beam 





Fig. 155. — Sirocco Fan. 



Fig. 156. — Conoidal Fan. 



blades were not so deep. Fig. 155, which he called the sirocco 
fan. This has been followed by the conoidal fans of the Buffalo 
Forge Company, Fig. 156. These are all used for forcing air. 
The cone wheel. Fig. 157, is used mainly on the vacuum system 
for sucking air from a given space. The cone center serves 
to guide the air from the center. The propellor or disc fan, 
Fig. 157, is used to exhaust air from a room. It is usually 



INDIRECT HEATING 



217 



placed in the partition or wall of the room from which it draws 
vitiated air and delivers it to the atmosphere. 

Fans are made with discharges in different directions and at 
times they may have more than one outlet. In Fig. 159 
different arrangements are shown. A represents a full housing 
top horizontal discharge, 5 is a full-housed top vertical dis- 
charge, C is a three-quarter-housed bottom angular discharge, 
D, a three-quarter-housed top angular discharge and F a full- 
housed multiple discharge fan. E represents a full-housed 
bottom vertical discharge. Fans are made either full or three- 





FiG. 157. — Cone Wheel. 



Fig. 158.— Ventilator. 



quarter housed with any methods of discharge to suit conditions. 
They are driven by direct-connected motors or engines or they 
may be belted to a prime mover. 

The manufacturers call a fan right or left if on facing the 
pulley side of the fan the discharge is to the right or left. 

Fans of the type shown in Fig. 154 are usually designed 
so that the peripheral speed of the fan wheel is equal to that 
produced by the dynamic pressure at the point of maximum 
efficiency. At this point the static pressure is equal to about 75 
per cent of the dynamic pressure while the velocity head is about 
25 per cent of the pressure. As the resistance is decreased the 
cubic feet delivery is increased and the total pressure falls until, 



218 ELEMENTS OF HEATING AND VENTILATION 

when there is no resistance around the fan, free discharge occurs 
with total zero pressure head, 50 per cent of the total head at 
best efficiency. This is all velocity head. The discharge at 




mmbk^MMi^mmmm^kmkmdM wimJ^^M^m ^ik-aimkMS^ 





Fig. 159. — Forms of Housings. 



this time is 145 per cent of the discharge at the best point. If 
on the other hand the discharge is closed off the static head 
increases until it equals the total pressure at zero discharge. 



INDIRECT HEATING 



219 



At this point the pressure is ii6 per cent of that due to a velocity 
equal to the peripheral speed of the wheel. The curve for the 
Buffalo Forge Company fans showing this change in pressure 
as the discharge is throttled is given in Fig. i6o. This curve 
has been prepared from one given by the company from results 
of tests. 

If in any case the resistance in the flues, ducts, heaters and 



120 












1 
































— 


h^' 


r>. 






















^.-^ 


















^ 


-^ 


sJ 


<ij^ 


p^ 












^100 

a 
o 






















\ 


ib 








1 




















h 




\ 




























\ 




\ 






2 






















N 






\ 




Ph 
























\ 




\ 


\ 


'S 
























\ 


\ 






bD 40 

C! 
(0 


























\ 






20 


























\ 


\ 






























\ 


































\ 



20 



40 bO 80 100 

Percentage of Volume at Best Efficiency 



120 



140 



Fig. i6o. — Relation between Pressure and Volume in Percentage of the Pressure 
and Volume from Fan at Maximum Efficiency as Given by Curves of the 
Buffalo Forge Co. 

casing amounts to hiw of water, this quantity represents 75 
per cent of the total head produced by the wheel, which is equal 
to the velocity head of the peripheral speed. 

Po 



0.75 



= P (Total pressure) . 



(98) 
(139) 



220 ELEMENTS OF HEATING AND VENTILATION 

Peripheral velocity of wheel = 66. 9^/ — —, ..... (loi) 

\o.7S 



= 60.9^^^!^, (140) 

6o 

where J = diameter of wheel in feet, A^ = R.P.M. Having the 

peripheral speed of the wheel, the diameter and number of 

revolutions must be found. This is determined by the square 

inches of blast area or " blast." 

This area is that through which the fan will discharge and 

give a velocity equal to the peripheral velocity of the wheel. 

ivd 
In most plate fans it is equal to — where w is the width of 

the blade at the tip, and d is the diameter. Now if Q is the 
cubic feet discharged per second, and Vp is the peripheral speed 
of the wheel in feet per second, the area of blast is 

Q wd 

'^=.".=7 ^^«) 

Since w is made equal to o./^d, while the widest part is 0.5 J, 
the value of a becomes 

a = —— =0.1336^-'. 



Hence 



0.133^^=7, 

Up 



and d may be found and then N. The width at body and tip 
are also known. With high pressures and small quantities the 
width is made smaller than 0.5^, while for large quantities under 
small heads the width is made large. 



INDIRECT HEATING 



221 



The inlet area in square feet is given by Parsons as 
0.000 54Q ^ .0 

Outlet area is given by 

^out = i-o to 1.25 inlet area, or this may be calculated with 
the flues and ducts. 

The radial depth of the blade near the edge is about 0.15Z), 
although another way would be to have the corner A, Fig. 161, 
fit i in. within the inlet opening with a clearance of about 






-|Tf" 


4 ij 

'\< — OAd — H 



Fig. 161. — Approximate Wheel Dimensions. 

f in. from the casing. This with the outer diameter will fix the 
radial depth. 

The power generated by a fan consists of three parts: (a) 
that required to give the air velocity, (b) that required to 
change the intrinsic energy, and (c) that to do the external work. 

The first amount is given by 

Work per second = M — = MK^ — . . . (141) 

2g 2g 

M = mass per second, 
zj = velocity of discharge in feet per second; 
F = peripheral velocity of fan; 
ir=percentage factor. 



222 ELEMENTS OF HEATING AND VENTILATION 

The second item is given by 

Work per second = If M-^-^ — — ^-^ . . . (142) 
^ L0.405 0.405 J ^ ^ ' 

po, pi, the pressure per square foot at outlet, inlet, in 

pounds. 
Vo, Vi, the volumes of one pound of air in cubic feet. 

The third amount is given by 

Work per second = If [^0^0— ^ a]. . . . (143) 

The sum of these is equal to the total work. 

[7) 'hi) i) -Di I 
+-T^^—-V^ + poVo — piVi 

= M[— + Y—[poVo-piVi]\, . . (144) 



but 



Therefore 



M = av4^ and v = KV. 



Work=-^ [^--+r— 7(^«^«-M)J 

Eq. (145) may be simplified by assuming that the intrinsic 
energy is not altered and that the specific volume does not 
change during the small change in pressure. This gives 

Work = ^g+(^-AK] 

= ^K+fc] = '^ff, • . . . . (146) 
H = total or dynamic head. 



INDIRECT HEATING 223 

Now 

^ is — (147) 

/. Work per second = -5^ — = i^iF3 (148) 

Q = aV (149) 

From Eqs. (147) (148) and (149) the important relations, 
that Q varies as V, H as V^ and work per second or power, as 
V^, are seen. These relations are shown by test data and by the 
tables which follow. These are prepared from the catalogues 
of the manufacturers. Only a few values are given, but in any 
case the relation can be used to find the results under different 
conditions. 

Thus from the table it is seen that as the diameter of the 
wheel increases, the number of revolutions per minute to pro- 
duce a given pressure will decrease, the product of speed and 
diameter being constant. The blast area varies as the square 
of the diameter, and since in any column the velocity is constant, 
the quantity discharged will vary as the square of the diameter. 
The velocity being constant and the quantity varying as the 
square will make the power vary as the square of the wheel 
diameter in any column of equal pressure. To care for differences 
in pressure, it will be remembered that pressure varies as the 
square of the velocity and hence the speed of a given wheel 
will vary as the square root of the pressure, and the power will 
vary as the three halves power, while the quantity will vary 
as the speed or the square root of the pressure. 

Thus I oz. pressure with a wheel 22 ins. in diameter requires 

896 R.P.M. with a discharge of 2 116 cu.ft. and 1.07 H.P. A 

22 
36-in. wheel will run at — X896 or 548 R.P.M. It will dis- 

/36\2 
charge 2116XI — ) or 5630 cu.ft. if the same proportions for 

width are used, while if these are changed the result will be 



224 ELEMENTS OF HEATING AND VENTILATION 

different. In some tables it is seen that the discharges are not 
so proportioned and this means a change in the proportion of 
the width. 

The power required will vary as the quantity, since the 
pressure is the same 

H.P. = 1.07^ = 7.87, 
'2116 ' ' 

For 2 oz. pressure for a 2 2 -in. wheel the following should be 
found : 

R.P.M. = 2'X896 = I264; 
2 = 2^X2116 = 2980; 
H.P. = 2' X 1 .07 = 3.00. 

In this way new columns may be made for the table or 
the data for different conditions of flow may be found. If 
reference is made to the curve of Fig. 160, the effect of chang- 
ing the pressure from that for which the table is built is 
seen. 

Before quoting the tables of the manufacturers of fans it 
is well to note the results obtained from the Sirocco fan, in 
which shallow blades are used. This fan gives higher dynamic 
pressures than the peripheral speed of the wheel. This is due 
to the better action of properly shaped blades and to the fact 
that there is less friction. The space taken by the fan is less 
than that required for other types, also the power is less. The 
makers claim a saving of | the space, \ the weight and | the 
power. However, for this fan the same variations of power^ 
capacity, speed and pressure as before noted is to be found in 
the tables. 

It rarely happens that the engineer designs his fan. By an 
understanding of the table the proper size may be selected. 

The following tables do not give all sizes made, but refer- 
ence to the catalogues of builders is recommended for closer 
figures. The discharge is in cubic feet per minute. 



INDIRECT HEATING 



225 







Sirocco Fan 








Buffalo 


Forge Fan. 




Fan 

No. 


Diam. 
Wheel. 




Tote 
P 


il Dyna 
ressure. 
Oz. 

I 


mic 
2 


Fan 
No. 


Diam. 
Wheel. 




Total Dynamic 

Pressure. 

Oz. 


i 


' 


2 


I 


6" 


Cu.ft. 
R.P.M. 
B.H.P. 


155 

1 145 
0.018s 


310 
2290 
0.147 


440 
3230 
0.42 


30 


22" 


Cu.ft. 
R.P.M. 
B.H.P. 


1497 

634 

0.37 


2116 

896 

1.07 


2989 
1264 
2.94 


ih 


9" 


Cu.ft. 
R.P.M. 
B.H.P. 


350 
762 
0.042 


700 
1524 
0.333 


1000 
2152 
0.95 


45 


32^' 


Cu.ft. 
R.P.M. 
B.H.P. 


3292 

430 

0.81 


4640 

607 

2.30 


6550 
6.49 


2 


12" 


Cu.ft. 
R.P.M. 
B.H.P. 


625 

572 
0.074 


1250 
1145 
0.588 


1770 
1615 
1.66 


70 


50" 


Cu.ft. 
R.P.M. 
B.H.P. 


8040 

280 

1.99 


1 1340 

394 

5.61 


160IO 

557 
16.39 


3 


i8" 


Cu.ft. 
R.P.M. 
B.H.P. 


1410 

381 

0.167 


2820 

762 

1.33 


3980 
1076 
3.75 


90 


64" 


Cu.ft. 
R.P.M. 
B.H.P. 


12950 

218 

3.21 


18300 

308 

9.06 


25800 

435 

25.52 


4 


24" 


Cu.ft. 
R.P.M. 
B.H.P. 


2500 

286 

0.296 


5000 

572 

2.35 


7080 

807 

6.64 


120 


85" 


Cu.ft. 
R.P.M. 
B.H.P. 


24200 

164 

6.00 


34300 

232 

17.05 


48300 

328 

47.85 


6 


36" 


Cu.ft. 
R.P.M. 
B.H.P. 


5650 

190 

0.665 


11300 
381 
5. 30 


15900 
538 
15.0 


160 


113" 


Cu.ft. 
R.P.M. 
B.H.P. 


43250 

121 

10.67 


61100 

174 

30.00 


86200 

247 
85.25 


8 


48" 


Cu.ft. 
R.P.M. 
B.H.P. 


lOOOO 

143 
1. 18 


20000 
286 
9.40 


28300 
403 
26.6 


200 


141" 


Cu.ft. 
R.P.M. 
B.H.P. 


70000 
17.16 


98900 

140 

48.95 


139500 
198 
138.0a 


10 


60" 


Cu.ft. 
R.P.M. 
B.H.P. 


15650 
114 
1.84 


31300 
228 
14.7 


44200 
322 
41.6 


250 


176" 


Cu.ft. 
R.P.M. 
B.H.P. 


116050 

79 

28 . 93 


163960 

112 

80.96 


231410 

158 

231.41 


1.2 


72" 


Cu.ft. 
R.P.M. 
B.H.P. 


22600 

95 
2.66 


45200 
190 
21.2 


63600 
269 
59.8 


300 


211" 


Cu.ft. 
R.P.M. 
B.H.P. 


T7479O 

66 

44.22 


246950 

94 

129.30 


348540 

132 

348.54 


15 


90" 


Cu.ft. 
R.P.M. 
B.H.P. 


35250 
76 
4.14 


70500 
152 
33.1 


99600 
214 
93.6 


350 


246" 


Cu.ft. 
R.P.M. 
B.H.P. 


245500 

57 

61.38 


346770 

80 

173.38 


489410 

113 

489.41 



To apply the tables, use data from the school building. 
The friction head in the pipes is 33 ft. of air, which is J in. of 
water. The loss in the two Vento heater stacks is 0.07 in. 
These with the loss in the fan may be taken as f in. The 
quantity to be handled is 1,820,000 cu.ft. per hour. 

3 ; 



f in. = 0.75 of peripheral speed; 
1 .00 = peripheral head ; 
F = 66.9Vi.oo = 66.9 ft. per second; 



0.133^2 = 



1820000 



66.9X60X60 

(^ = 7.54^ = 90.5^ 



226 ELEMENTS OF HEATING AND VENTILATION 

H e >i< B- 





DIMENSIONS OF SIROCCO FAN 



No of 


Diam. 














■ 
















Fan. 


of 


A 


B 


c; 


D 


E 


F 


c; 


H 


M 


i 


K 





1 


N 


Wheel. 






























2h 


15 


10 


9t^ 


14I 


15 


14 


13 


9i 


13* 


10^ 


10- 


i6f 


6? 


10 


3l 


3 


i8 


12 


iitV 


lyf 


18 


15 


I5i 


loi 


15* 


I2i 


12- 


19 


75 


12 


47 


3i 


21 


14 


13A 


20f 


21 


iH 


I7i 


12 


18 


14? 


13- 


21^ 


84 


14 


5i 


4 


24 


i6 


I5i^ 


23* 


24 


20i 


19^ 


13^ 


I9f 


I6i 


I5-=V 


24^ 


10 


16 


6 


Ah 


27 


i8 


I7r- 


26* 


27 


23 


22 


15 


2ii 


I8i 


I6t 


29 


II 


18 


6i 


S 


30 


20 


iSf- 


29f 


30 


25 i 


24i 


i6i 


22t 


20i 


17- 


32 


12h 


20 


74 


6 


36 


24 


22\r- 


3Si 


36 


30^ 


29i 


20| 


26t 


24i 


2ii 


38 


15 


24 


9, 


7 


^l 


28 


26^ 


41 


42 


35 


33-8- 


23^ 


29i 


28i 


23i 


44 


I7i 


28 


xok 


8 


48 


32 


30t^ 


47 


48 


30^ 


37i 


27 


32^ 


32 i 


27 


50 


20 


32 


lOi 


9 


54 


36 


33x1 


52i 


54 


44 


42- 


3ii 


35- 


36^ 


28i 


56 


22i 


36 


12 


10 


6o 


40 


37tI 


584 


60 


48* 


47- 


35 


36- 


40- 


32 


62 


2-^ 


40 


12 


II 


66 


44 


4ir6 


64i 


66 


53 


5i| 


.38 i 


39 


44 f 


It 


68 


27* 


44 


I3i 


12 


72 


48 


4SA 


70i 


72 


57^ 


55s 


42 


43^ 


aU 


74 


30 


48 


134 



DIMENSIONS OF BUFFALO FORGE FAN 



Size in 
Inches 


Diam. 
Wheel. 


A 


B 


C 


D 


E 


F&G 


H 


I 


J 


K 


P 


N 





R 


30 


22 


1I4 


III 


14^ 


I5i 


14^ 


111 


Hi 


lOf 


1I4 


14I 


I5i 


3 


7 


12! 


35 


254 


13- 


I3i 


I7tV 


i8t^ 


i6ii 


I3| 


I3s 


III 


I3i 


17 


174 


3 


7 


I4il 


40 


29 


15 


15^ 


I9t 


20^ 


I9i 


15 ft 


14* 


I2I 


15 


19 


19 


3 


« 


174 


45 


32| 


16- 


18 


22^ 


23 T^ 


2lV« 


18 


i5i 

I7t 


I3f 


i6i 


21- 


20I 


3 


8 


19 \ 


SO 


36 


18- 


20 


24^ 


26 


23 i 


20 


I4i 


l8i 


24- 


225 


4 


9 


214 


55 


39^ 


193 


22 


26H 


28, »« 


261 


22 


187 


15I 


I9f 


26- 


24 


4 


9 


23-4 


60 


43 


22- 


24 Vs 


29^ 


3ii 


28 


241V 


19, 


i6| 


22i 


261 


265 


5 


10 


25 


70 


50 


26 


28* 


34i 


36i 


34^ 


28i 


22 


loi 


26 


34- 


30i 


5 


II 


30 


80 


57 


29i 


32 tv 


39i 


41* 


37^ 


32 ^i, 


24i 


2ii 


29| 


39^ 


35 


6 


12 


34s 


90 


64 


33- 


36i 


44 


46i 


44 


36i 


26- 


23i 


334 


43- 


38, 


6 


14 


39 


100 


71 


37- 


40 A 


48- 


5l| 


47 


40 fk 


28- 


2,S? 


37 i 


46i 


43- 


7 


16 


43 s 


no 


78 


41 


44 f 


53- 


56^ 


51 


44t 


31- 


28 


41 


51^ 


47 i 


7 


18 


47i 


120 


85 


AAi 


48 y« 


58- 


6ii 


56 


48 V« 


34 


.30i 


44^ 


55- 


51 


8 


20 


524 


130 


92 


48* 


S24 


63^ 


67 


61 


524 


364 


33 


484 


60^ 


54s 


8 


22 


564 


140 


99 


52^ 


56VV 


68- 


72i 


6S| 


561% 


39t 


35l 


52i 


64J 


59f 


9 


24 


60| 


ISO 


X06 


56 


6o| 


73- 


77i 


70I 


6of 


42i 


37i 


S6 


694 


64* 


10 


26 


65 i 



INDIRECT HEATING 227 

This is large; 

^• = 36"; 

R.P.M.--^^X6o = i69. 

7-54^ 

The power to drive the fan is given by 
1820000 X 14.7 X 144 



Power 



3600X550X53.35X530 
-2 



0.40s, 



ri><66^ ^x405( ^)/ _r^i.:4o.\i 

L 64.32 0.405^^^^^ ^^ ^V L34.1J /J 

=2.5 H.P. with an efficiency of 35 per cent. This would 
require 7.1 H.P. 

It is better, however, to use tables of the makers for sizes and 
dimensions. 

From the table, since i in. is approximately J oz., a 99-in. 
wheel at 141 rev. will be required to deliver 32,800 cu.ft. of air 
per minute. This requires 8.14 H.P. To deliver just 30,000 
cu.ft. this fan will be run at 

^^1^X141 = 129 R.P.M. 
32800 ^ 

The power consumed will be 

^yx8.i4 = 6.2H.P. 
141/ 

The pressure will be 

i2o\2 

Xi=o.42 oz. 

141/ 

If this pressure is not sufficient the fan will have to be run 
faster and the quantity will be changed from the point of max- 
imum efficiency, as there will not be the same relation between 



228 



ELEMENTS OF HEATING AND VENTILATION 





d b 


ffl^PraTCTW 






i 


k 



velocity head and friction head as that at a proper speed anct 
pressure. 

For a Sirocco fan a 6o-in. fan at 134 R.P.M. would be 

required, and this would use 7.48 
H.P. This would be treated in 
the same manner as above to get 
exact conditions. 

The dimensions of the hous- 
ings of these fans would be found 
from the tables. 

The further application of 
this method of heating will be 
applied to a shop building shown 
in Fig. 162. 

In this building there are 
11,200 sq.ft. of wall space of 
i6-in. concrete, 13,600 sq.ft. of 
glass, 20,000 sq.ft. of concrete 
roof and 750,000 cu.ft. of air. 
There are 300 men employed in 
the building. 

The amount of air required 
for ventilating would be 

300 X 2000 = 600000 

cu.ft. per hour. 



<^ 


f 




a a 






a a 






D 




' 


a D 
a □ 


9 

> 




□ D 






D a 




J 




'^ 



Fig. 162. — Shop Building. 



This is much less than the 

volume of the room, and with as 

much window space as is here used the leakage from the windows 

will keep the air sufficiently fresh so that a heating system 

will be used in which the air is recirculated from the shop. 

The heat required is found as follows : 



Temperature shop, 55' 
K for glass, 0.96; 
K for concrete, 0.26; 
K for roof, 0.30. 



F. 



INDIRECT HEATING 229 

5" = (55 — o) [o. 26 X 1 1 200 +0.3 X 20000 +0.96 X 13600] ; 
= 55X21968 = 1208240 B.t.u. 

If the air is to be heated to 85° F., the amount of air to be 
■circulated will be : 

1208240 

— — =2014000 cu.ft. per hour, 

0.02X30 ^ 

or about three changes of the volume of the room. 

In some cases this air might be carried through a filter before 
entering the fan again, thus cleaning the atmosphere, and in case 
of mill heating the proper humidity might be obtained in this 
way. 

Since 2,000,000 cu.ft. per hour is a large quantity, it might 
be advisable to separate the system into two parts. Moreover 
the crane run-way must be left clear, and the only way of 
distributing to both sides if one fan were used would be to cross 
over at the end of the building or use an underground duct. 
For simplicity and economy it is well to place heaters near 
the center of the building. 

In this system quietness is not so important as smallness of 
pipes, and for that reason high velocities of 2500 ft. per minute 
wiU be used in the pipes, while 500 ft. will be used at ends of 
branches. There will be an opening in each bay, as shown on 
Fig. 162, for space beneath gallery and roof. The velocity 
through the heater will be 2000 ft. per minute. 

The temperature of the air leaving is 85° F., which with 
zero air and 5 lbs. steam will require four sections of Vento 
heaters. The entering air is at 55°, which requires two sections. 
Hence the difference, or two sections, must be used to heat the 
air from 55° to 85°. 

At 2000 ft. the heat transmission for the two sections is 

2380X4-2670X2 -D , 

— or 2090 B.t.u. 

2 

The heating surface required will be 

12082 40 

= S78 sq.ft. 

20QO ^ ' ^ 



230 ELEMENTS OF HEATING AND VENTILATION 

The amount per heater will be 289 sq.ft. and the amount per 
stack will be 145 sq.ft. The area required through heater will 
be 

^""7"°° 8.4 sq.ft. 



2000 X 60 



II 50-in. sections with 5-in. centers will give this. 

To cut down the area required a higher temperature will be 
used. Suppose five sections be used in the heater; this means 
then that the condition is that of a 5-heater system where the 
air has passed through two sections. The temperature of the 
air leaving is then 120° F. and the heat transmission is 

1950X5-2670X2 o -n ^ 
-^ = 1803 B.t.u. 



The heating surface is then 

1208240 
1803 



670 sq.ft. 



or 335 sq.ft. on each side of the building. This means 112 
sq.ft. to each stack. The air now used will be 

1208240 

—7 — : 7 = 030000 cu.ft. 

o.02X(i20-55) ^^ 

or a little over one change per hour. The amount for each heater 
is 7750 cu.ft. per minute. The area through the heater should 
then be 

^=^^ = 3.9 sq.ft. 
2000 ^ ^ ^ 

A 9-sec. 50 in. high 4! in. centers would have the correct heating 
area, but the area for the air passage is 5.85 sq.ft. A lower 
velocity must then be taken. Suppose 700 ft. be assumed. 



INDIRECT HEATING 231 

Then i sec. will give 40° F. and 4 sec. 118° F. The heat per 
sq.ft. for the three sections will be 

1200X4— 1600 
= 1 100 



■r r. -. 1208240 

H.S. per stack = -———T = 182. 

^ 2X3X1 100 

This will not give the desired result. The first result is the 
best combination. 

A . 1 1 r 2010000 

Air by each fan = = loooooo, 



or 16700 cu.ft per minute. 

Air to each floor 8350 cu.ft. per min.; 
Air to each branch 4175 cu.ft. per min.; 
Air to each outlet 1040 cu.ft. per min. 



1040 
Area of outlet — — = 2 sq.ft. 
500 



1040 

Area of last section X 144 = SQ sq.m. 

2500 -^^ ^ 

D = g. 
Area of 2d section from end 
2080 



2500 



X 144 = 118 sq.m. 



Area of 3d section = 177 sq.in. i^ = 1 5. 

Area of 4th section = 236 sq.in. Z) = 17^ in. 

Area of vertical riser, 462 sq.in. D = 24. 

Area of vertical riser from fan = 924 sq.in. =31X31. 



232 ELEMENTS OF HEATING AND VENTILATION 

Drop in pressure due to friction. 

^ 0.02X25 42^ 
ist section, n = — X z~ = 18 ft. of air 

•75 64 

= 0.26 in. of water. 



2d section, A = 0.26 in.X = o.iq in. of water. 

12.5 



xd section, h = o.26 in.X — = o.is in. of water. 

15 



4th section, h = o.26 in.X =0.1^ in. of water. 

17.5 ^ 



Riser ist to 2d, 0.20 X X — = 0.0=:. 

17-5 25 

^r . . ^ 9 10 

Mam riser, 0.26 X — X — = 0.03. 
31 25 

422 

Loss in bends = 0.1 5 -7— =9 ft. air or 0.13 in. water. 

Total loss in pressure : 

Last branch and nozzle 0.05 (assumed) 

Bend o. 13 

Last section 0.26 

2d section 0.19 

3d section 0.15 

4th section 0.13 

Bend o. 13 

2d floor riser o . 05 

ist floor riser o . 03 

Bend o. 13 

Fan o . 20 

2 section heater 0.45 

Total 1.90'' 



INDIRECT HEATING 



233 



This is the total resisting pressure. The dynamic pressure is 

— — = 2.6 ins. Use 2 oz. Then from the tables two No. 70 
•75 ^ 

steel-plate fans with wheels 50 ins. in diameter will be required 
when run at 557 R.P.M. and each using 16.39 H.P. These 
each give 16,011 cu.ft. The Sirocco table gives 2 No. 6 fans 
with diameters 36 ins. at 



^e^ 



^5 



538 R.P.M. and using 15.0 
H.P. These each give 
15,900 cu.ft. They may 
be speeded down to give 
the exact discharge, as 
was done with the school- 
house fan. If larger pipes 
could be used and the area 
through the heaters made 
greater to cut the velocity 
to one-half its value, the 
resistance should be J of 
this or J oz. This would 
require two No. 100 fans 
of 71 ins. diameter at 197 
R.P.M. and would use 4. 11 
H.P. giving 16,610 cu.ft. 

The Sirocco fan for 
this service would be a 
No. 9-54 ins. diam. fan at 
179 R.P.M. using 4.20 H.P. 
and giving 17,950 cu.ft. 

In all cases it is advisable to use as low a velocity as possible, 
but in some cases the size of pipe is the important matter. 

In cases where steam engines are employed and the exhaust 
steam is used in coils, the excessive power loss is not important, 
as it is changed into heat and used in the building. This same 
is true in a plant using electric power when it is made on 
the premises and the exhaust steam is used for heating. 
It is simply a matter of cost of production of power, as electrical 




Fig. 163. — Small Factory. 



234 



ELEMENTS OF HEATING AND VENTILATION 



power or thermal power. If.i B.t.u. of heat can be produced 

I 



as heat in the coils at 



50000 



ct. while I B.t.u. of electrical 



energy costs ct., it is evident that the power consumed 





Fig. 164. — Mill Heating, Using Buttress. 



by the fan should be reduced to as small a quantity as possible 
if an electric motor is to drive it. 

The following figures are prepared from cuts showing the 
work of the B. F. Sturtevant Co. 

Fig. 163 illustrates a method of introducing air into a small 
factory, while Fig. 164 shows how underground ducts and but- 
tresses may be used in mill buildings. The use of brick ducts 



INDIRECT HEATING 



235 




// 
// 
// 



^ 



i i 




Fig. 165.— Damper for Wall Duct. 




Fig. 166. — Indirect Heating of Theater. 



236 ELEMENTS OF HEATING AND VENTILATION 

underground is important in many cases. The problem is the 
same as with metal, the constant / being increased as mentioned 
earlier. In Fig. 165 the form of damper used in such a plant is 
given; such dampers must be operated from the floor of the room. 
This arrangement is not as advantageous as one in which the 
air is carried in the interior of the building, as there is loss of heat 
through the walls of the flues. Similar buttresses may be used 
to remove the foul air, although unless the product of manufac- 
ture vitiates the air there are so few occupants that this air 
may be recirculated, using screens or filters to remove dirt. 

Fig. 166 illustrates the method of applying this system 
to a theater. 



CHAPTER IX 

FURNACE HEATING 

As described in Chapter I, furnace heating is a system in 
which hot air is introduced from a furnace into the rooms to be 
heated. The air may be introduced to the heating tubes of the 
furnace from the outside or it may come from the interior of the 
building through the recirculating duct. This latter method may 
be used in residences or in buildings where there are not so many 
occupants, the leakage from the window^s and doors giving 
sufhcient fresh air. The former method must be employed in 
schools, churches or audience rooms heated by furnaces, on 
account of the large amount of fresh air for ventilation. 

The first consideration in this method of heating, as in all 
methods, is the necessary heat to care for the losses, then the 
amount for the ventilating air, and finally one must consider 
the temperature at which the air must enter in order to supply 
the heat loss before being reduced to the room temperature. 

The method of Chapter V is used to find the heat losses 
and then the assumed amount of air for ventilation is used to 
find the temperature at which this air must enter. 

''='-+5:^' (^50) 

where /< = temperature of entering air in deg. F. ; 
tr = temperature of room air in deg. F. ; 
5" = heat loss per hour in B.t.u.; 
F = volume of air per hour in cubic feet. 

The air assumed as the ventilating air or leakage air may 
give so high a value of h that the amount of air must be increased. 
This does not necessarily mean that the air from the outside 

237 



238 



ELEMENTS OF HEATING AND VENTILATION 



must be increased, but that passing through the heating tube. 
A large part of this may come from the recirculated air in resi- 
dences. 

The house of Chapter V will now be examined. As men- 
tioned in Chapter VIII an examination of the air supply to the 
various rooms will show that the leakage air assumed is too 
small, as the temperatures are all high. If 130° F. is assumed 
as a good temperature for this air the quantity in cubic feet at 
70° will be that found in the table below which is prepared in 
addition to those of Chapter V for the furnace system of heating 
this house. 











Total Heat for Various Amounts of 




Heat Loss, 


Ventilation, 
Cubic Feet 






Outside Air. 




Room. 














Hour. 


per Hour. 




Full Outside 
Air. 


One-half 
Outside Air. 


No Outside 
Air. 


I 


16810 


14000 


130 


36500 


26600 


16800 


2 


11792 


9600 


130 


25000 


18200 


1 1 800 


3 


1745 


1450 


130 


3800 


2800 


1700 


4 


6890 


5700 


130 


14800 


10800 


7000 


5 


8740 


7300 


130 


19000 


13900 


8700 


6 


10635 


8900 


130 


23200 


17000 


10600 


7 


14050 


1 1 700 


130 


30400 


22300 


14000 


8 


8750 


7300 


130 


19000 


13900 


8700 


9 


2170 


1800 


130 


4700 


3300 


2200 


10 


7680 


6400 


130 


16600 


12200 


7700 


II 


8330 


7000 


130 


18200 


13400 


8300 


12 


2840 


2400 


130 


6200 


4600 


2800 




100432 


83550 




217400 


159000 


100300 



The column marked total heat with full outside air has been 
computed by the formula : 

H = 0.02V {ti- to) (151) 

while the column for one-half outside air has been found by 

i3' = heat loss-|-|Fo.o2[/r — /o] .... (152) 

= 0.02V[T,-TrH{Tr-To)] 
2 



= 0.02F 



[--?-•] 



(iS3) 



FURNACE HEATING 239 

Since 

Heat loss = 0.02 Ffri-Tr] (154) 

V in all of the cases is the volume at 70°. The computa- 
tions are made with a slide-rule in all work of this nature, as 
the original data and the variation in conditions do not warrant 
a greater degree of accuracy. 

The table shows well the cost of ventilation. With no fresh 
air 100,000 B.t.u. are required per hour. With 50 per cent 
efficiency of furnace and with coal of 14,000 B.t.u. this means 
14 lbs. of coal per hour. With the air taken entirely from the 
outside, the heat required amounts to 217,000 B.t.u. and re- 
quires about 31 lbs. of coal per hour. The leakage mentioned, 
in the table of Chapter V of 30,000 cu.ft. from the outside is 
about three-eighths of the amount necessary to keep the enter- 
ing temperature at 130° F. and if this came in it would mean 
the supply of 144,000 B.t.u. per hour, or 21 lbs. of coal. The 
full amount of air would care for about 45 persons, while the leak- 
age of Chapter V would care for 18 persons, a number which 
would be too large even for this house for continuous use. Hence 
the value, and necessity even, for inside circulation in residences 
is quite evident. In most cases the leakage, in on the windward 
side and out on the leeward side, is sufficient to care for the 
ventilation of the rooms, and this amount of leakage is likely 
to occur though all of the air for the furnace is taken through 
the inside recirculation duct. 

Having found the amount of heat, the next step is to decide 
on the location and size of the various pipes, flues and registers. 

The location of registers is important. If located in the wall 
they may interfere with the placing of furniture and are limited 
in size according to the size of the partition, while if placed in 
the floor, although better as far as size and directness are con- 
cerned, they mean a cutting of carpets or floors, to which some 
householders object, and they collect dust and dirt. When 
placed in the floor, however, they offer a more direct path and 
for that reason it is very advisable to place them in this manner 
on the first floor, where there is little head causing flow. 



240 ELEMENTS OF HEATING AND VENTILATION 

The head causing flow is the difference in weight between 
the column of hot air and cold air, and as mentioned in Chapter 
VIII, this head, expressed in feet of hot air, is, 



_r \RT2 RTi) j Ti-T2 



RTi 

ri = absolute temperature of inlet air; 
r2 = absolute temperature of air at bottom of heater; 
= Tr approximately. 

If this is appHed as before to the various heights from 
registers to base of heater, say lo, 20 and 30 ft., the following 
heads result, for 

/i = 130; 2^1=590; 

/2 = 60° F. (due to mixture of some cold air) : 

^1 = 1-35; 
7/2 = 2.70; 

^3 = 4.05- 

The pipes leading to the vertical flues or stacks are known 
as leaders. In these, the velocities will vary with the sizes of 

the pipe I fixing the hydraulic radii, ^ ) , with the length of the 

run, the number of bends, etc. The following problems will 
give an idea of the results to be expected. (See p. 198.) 

I St. Find the velocity in the pipe to a first-floor register with 
a 15-ft. run of 12-in. pipe and a bend of radius equal to the 
diameter. 



2p<13S =8.o3VT5 = S.4. 

Vx+°-:^+..5Xx+x.5 



2d. Find the velocity to be expected in a 14X3^ flue run- 



FUKNACE HEATING 241 

ning to second floor with two sharp right-angle turns and lo 
ft. of lo-in. pipe. 



F= ?i^ = 8.o.V7,=6.8. 

/ 0.02X10 , 0.02X10 , , ' 

^ 12 "^12X35 

In this way the velocity may be found for any given condi- 
tion, but in general the velocity for the various floors will be 
assumed. The values given below are those which may be 
expected in practice : 

ist floor, 4.0 to 5 ft. per sec; 
2d floor, 5.0 to 6.5 ft. per sec; 
3d floor, 6.0 to 7.5 ft. per sec. 

Having the velocities to the different floors, the areas of pipes 
and flues are found. 

Area = -:^^ ^^^6) 

Thus where 6" = the factor to care for temperature as found in 
the table of p. 209, for room'2 of the house considered in Chapter 
V, the area will be 

. 9600X1. 11X144 

Area = ——7 = 106 sq.m. 

4X3600 ^ 

This requires a pipe ii| ins. in diameter. A 12-in. j ipe 
will be used. 

The area of the registers will be fLxed by the allowable velocity 
of discharge. This may be taken as 4 ft. per second on all 
floors, giving 

144FC cV . . , . 

Netareareg. = = m sq.m. . . . (iS7) 

^ 14400 100 ^ ^ ^'^ 



242 



ELEMENTS OF HEATING AND VENTILATION 



Since the net area is 66 per cent of the gross area of opening into 
which the register fits the area of the opening is given by 

l.A.A.Vc 

Area opening = —zttz = o.oi 5 Vc. . . (1 ^8) 

° 0.66X14400 -^ V / 

In the case above this equals 

0.01 5 X 9600 X 1 . 1 1 = 1 60 sq.in. 

A io''Xi6'^ register would be required. 

If vent stacks are used Hoffman recommends that their 
areas be made 0.8 of the heat stack areas. 

The pipes leading to the stacks are in some cases made larger 




m 



F I 



Fig. 167. — Furnace with Flat 
Bonnet. 




QD 



Fig. 168. — Furnace with Conical 
Bonnet. 



in area than the stacks supplied by them to cut down resistance. 
This must be done in cases of long runs, although in short 
runs it is not necessary. 

Before applying these formulae, however, it is well to plan 
the location of the heater and the location of the various flues 
or stacks. 

Stacks should be run in the inside partitions, as there would 
be considerable heat loss if placed in outside walls. Circulation 
is better cared for if appHed here, as the hot air rising naturally 
starts the cold air across the floor from the other side and thus 
gets the air in motion. If placed in an outer wall the cold air 
from the wall may start a down current of air in the stack, 
thus choking off the supply. The furnace method of heating 
is dift'erent from steam heating, in which radiators form strong 



FURNACE HEATING 



243 



lip currents due to the higher temperature. The principal 
objection to furnace heating is the absence of a positive 
circulating force. 

The leaders or pipes leading across the cellar from the heater 
are taken from the top of the casing around the heater. This 
casing may have a flat top as shown in Fig. 167 or it may have 
a cone top or bonnet as shown in Fig. 168. Although the flat 
top receives the hot air more directly from the furnace it means 
that there will be more head room needed and a full right-angle 
turn will have to be used. The distance above the castings 
to a flat top should be at least 8 or 9 ins. and this could be used 
to advantage on a slanting side cutting down the bend to 45 
or 60° instead of a right angle. The slant height of the bonnet 




Fig. 169. — Register Floor Box. 



should be about 3 ins. greater than the largest pipe to be taken 
from it. To aid in sending the air to the edge with a cone top, 
an inside conical center is used as dotted in Fig. 168. This 
sends the air to the outside. Sometimes a long leader is taken 
from the center of the top so that it may get a better supply 
to overcome the friction of the great length or the long pipes 
may be taken from the rear side of the top, but never 
directly over the point where the cold air enters nor near the 
edge of a flat top where it might start currents along the cold 
casing. To aid the circulation in long pipes or to pipes on the 
exposed sides of a building the leader is sometimes continued 
inside of the bonnet with an enlarged hood, so that the hot air 
may be directed into it, and in some cases positive circulation 
is attained by connecting certain leaders to a number of the heat- 



244 



ELEMENTS OF HEATING AND VENTILATION 



ing tubes of the furnace. The furnace should be so placed that 
the runs for the leaders on the exposed sides, usually the north 
and west, are shorter than the others, but the heater should be 
placed so as to make all as short as possible. 

The leaders are carried to the register boxes, Fig. 169, for 
the floor registers of the first story, or the shoes or boots, Fig. 
170, at the bottom of the heat flues or heat stacks which run 
to higher floors. The boxes for the floor registers should be 







Fig. 170. — Shoes. 



Fig. 171. — Damper. 



made with no projecting fins to obstruct the flow of air and the 
4-in. collar at the bottom should be connected with the leader 
by an elbow at least equal to the diameter of the leader. The 
register box is about 4 J to 6 ins. deep to allow the air to reach the 
ends of the register face with little obstruction. The elbow 
should fit the pitch of the pipe. The pitch should be not 
less than i in. per foot. This pitch is advisable for starting 
the circulation, although for a pipe running full of a fluid with 
a definite dift'erence in head between the ends the velocity of 



FURNACE HEATING 245 

the fluid is theoretically independent of the pitch. In furnace 
work, however, the difference of head is small and the substance 
has such a small density that there may be currents in two direc- 
tions in the same pipe and for these reasons, although the formulas 
for fluids have to be used, there is the need of considering the 
peculiarities of the substance. Thus pipes are pitched as much 
as possible and circulation is aided thereby. 

The leaders are connected to co lars about 5 ins. long, which 
are attached to the bonnet of the furnace. The tops of the col- 
lars should all be on the same level so that they will all offer 
the same resistance to flow. All leaders except one should be 
provided with tight-fitting dampers, Fig. 171, so that the heat 
may be cut off when necessary. Some one leader should 
be arranged so that it cannot be cut off in order that there 
may be no danger of closing all outlets and heating the 
air within the casing so much that fires may occur. 

If there is only one outlet, as is the case at times in church 
heating, this connection should be without a valve or damper 
of any kind. 

The leaders for the second floors or for registers placed in 
the walls are attached to boots or shoes, Fig. 170, which form 
the lower parts of the flues or stacks. 

The shoe ^ or ^ is intended to be used when the leader is 
at right angles to the partition, while C and D are used when 
the leader runs parallel to the partition. E and F are employed 
when elbows are used to join the leader and shoe. Shoe B 
requires no bend at the end of the leader to accommodate the 
pitch and therefore should offer small resistance. The slanting 
back of A is of little value. 

The shoe shown at C is used when it is necessary to offset 
for the leader. The stacks are made of single or double thick- 
nesses of tin. The ordinary partitions are made of 3 X4 or 2 X4- 
in. studs placed 16 ins. apart. These wifl allow one to use 
13X4- or i4X4-in. stacks as the largest single stacks and in 
that way the amount of heat taken for a single register face is 
limited. Stacks are usually made rectangular in form on account 
of space limitation, but the nearer the form approaches a circle 



246 



ELEMENTS OF HEATING AND VENTILATION 



fl 
^ 



or square, the better it is for carrying a fluid. The fric- 
tion of a conduit depends on the reciprocal of the hydrauKc 
radius which is the ratio of the area of the section to the perim- 
eter of the sections and this is larger for the circle and square 
(Id) than for any other form of area. Stacks are some- 
times made with double walls, to cut down radiation and 

to prevent charring the wood 
if hot. Some advise having single- 
thickness stacks covered with as- 
bestos paper. These stacks end in 
register boxes, Fig. 172. A repre- 
sents the ordinary form where the 
box is placed at the end of the riser 
or stack and B show^s one which 
does not require the full width of 
the stack. The figure also illus- 
trates a box which takes part of 
the supply of a stack, the remain- 
ing part going to the room above. 
This method is used at times, but 
it is not the best way to supply 
heat owing to interference. For 
privacy it is not well to put two wall registers opposite each 
other on the same stack. 

The box D is one in which a circular top register is to be 
used while C illustrates a method for first-floor registers in order 
to increase the area of flue. To increase the area of the flue for 
first-floor wall registers, the plaster and base board are omitted 
at these points, and in this way an extra inch may be obtained. 
By using the box shown at C, however, in which the special 
register casting fits over the sides of the box as shown in Fig. 
173, a much greater area necessary for large first-floor rooms- 
is obtained. The registers are held in place by the clips shown 
on the boxes. The stacks are sometimes turned to enter floor 
boxes on an upper floor and it is then necessary to use an elbow,. 
A or B, Fig. 174. When the partition through which the stack 
passes is directly over the cellar partition an offset, C, Fig. 174,. 





Register Boxes. 



FURNACE HEATING 



247 



is used on which to attach the boot. Fig. 175 shows the appH- 
cation of these various fittings.' 

The tin used for pipes and stacks is made of soft sheet steel 



nnnnnnnn 
jonnnnnnn 
mnnoDDDn 
UDDDDDnnn 
DDDDDDDQ 





Fig. 173. — Special First Floor 
Wall Register. 



Fig. 174.— Elbows and 
Offsets. 



n 



Bz: 




Fig. 175. — Stacks, Shoes, and Leaders. 



coated with tin. Originally it was made of wrought iron. 
Tin is gauged by numbers or letters. The trade terms from 
56 lbs. to 100 lbs. mean the weight of a box of 100 14^X20^' 



248 ELEMENTS OF HEATING AND VENTILATION 

sheets, while between weights of 107 lbs. and 215 lbs. to the box 
of 100 i4"X2o'' sheets, the tin is known as I tin; IC being 107 
lbs. to the box, IXL, 128 lbs; IX, 135 lbs.; IXX, 155 lbs. up 
to IXXXXX, 215 lbs. 

IC, IX or IXX tin is used for pipe work, the latter for pipes 
over 12 ins. in diameter. The piping and stacks are often 
wTapped in asbestos paper to make all the joints tight, although 
this does not cut down the heat loss very materially. In fact 
the use of non-conducting material or air space with double- 
thickness stacks is not necessary for stacks on interior walls, 
as any heat escaping is used to warm the house. To cut down 
loss in the cellar, some type of air-cell covering or thick pipe 
covering might be of value to keep the cellar cool. This heat 
escaping in the cellar is not wasted, however, unless the cellar 
is heated too much for the proper storage of vegetables and fruits. 
The heat from these pipes warms the cellar and thus cuts down 
the loss through the floor from the first-floor rooms. 

In running the leaders from the heater, endeavor should be 
made to reduce the resistance to a minimum even though 
special cutting must be made on the fittings of the piping to suit 
the angles. Thus the dotted position for the leader of Fig. 167, 
although cheaper to make because of the use of standard elbows, 
is not the one to give the better flow of heat which should be 
the aim in all designs. 

For school heating it is advisable to bring the air in from 
a wall register placed six or eight feet from the floor and to have 
a vent register near the same point at the floor level. In some 
cases this is not possible and floor registers have to be used. 
The ventilating stack is sometimes made effective in such 
installations demanding ventilation, by having a furnace or 
hot pipe at the base of a stack which heats the stack air and 
causes it to rise. This produces a draft which sucks impure 
air from the proper part of the rooms of the lower story while 
the hot air is made to pass over restricted areas at the upper 
floors, causing an injector action and sucking the air from the 
room. If the furnace gases could be carried up through a central 
iron flue in a brick ventilating stack, the heat from the flue 



FURNACE HEATING 



249 



ivould cause the air around it in the stack to rise, drawing in 
air from the various rooms on the stack to replace it. 

At times it is necessary even with hot-air furnaces to use 
fans to produce the necessary circulation, Fig. 176. This occurs 
in large work only when some of the rooms to be heated are at 
considerable distance from the heater. In school work or other 
large buildings, several heaters may be placed at convenient 
locations, each heater caring for a set of adjacent rooms. This 
method requires several chimneys, but these are easily built 
when the necessary ventilation flues are formed. 




Fig. 176.— Fan Circulation ^vith Twin Hot-air Furnaces. 

The principles are now apphed to the house considered 
earher and the layout of heater and piping of Fig. 177 is made 
for the cellar, in conjunction with the plans of the rooms. Fig. 
178. The heater is placed near the north and west side but 
the pipes are mainly on three sides of the heater. Hence the 
room behind the heater or the central passage of the cellar would 
liave been far better had the use of the cellar rooms and the loca- 
tion of the chimney permitted it. In many cases the location 
of the heater is a compromise between what should be and what 
is needed. 

The length of the pipes to the various rooms should be as 
short as possible, but here again the demands of the owner must 



250 



ELEMENTS OF HEATING AND VENTILATION 



be considered. Thus for room 5, the pipe could have been 
made shorter had the use of room permitted the register to be 




P K 



Fig. 177. — Pipe and Heater Arrangement. 



««- p' 



I2"tri2" 



¥ 



^ 



■> 



y. 



3C 



10^.12^1 



" I 10x12" 



2ND FLOOR 



15V,16". 



Return- 
is '14' 



y 



¥=^ 



^ 



lOlx 14^ 

4V14'D- 



^ 






I I 1 Qv . „ 



, A ^ 



1ST FLOOR 



Fig. 178. — Arrangement of Outlets. 



placed near the partition. Fig. 178 shows the location and 
size of the registers and flues. 



FURNACE HEATING 



251 



The application of the foregoing principles to the house 
gives the results in the following table: 



B 


Venti- 


Leader. 


Stack 


Register. 


Vent Stacks. 


Vent Registers. 


o ■ lation. 


Area 


Size. 


Area 


Size. 


Area. 


Size. 


Area 


Size. 


Area 


Size. 


I 
2 

3 
4 
5 
6 

7 
8 

9 

lO 

II 

12 


14000 
9600 
1450 
5700 
7300 
8900 

II70O 
7300 
1800 
6400 
7000 
2400 


180 

123 

19 

73 

93 

114 

100 

63 

17 

57 

60 

23 


15 
13 
5 
10 
II 
12 
(12)10 

9 
(5)8 

9 

9 
(6) 10 


■ 

(95) 
60 

15 
52 
57 
(20) 


1-4 X 14 
1-4 X 14 

1-4X12 
1-4X13 

1-4 X 14 
1-4 X 14 


233 

160 

24 

95 

122 
148 
(196) 
122 
(30) 
107 
116 
(40) 


15X16 
10X16 

10X10 
10X14 
10X16 
12X12 
10X12 
10X10 
10X12 
10X12 
10X12 


125 
83 
13 
52 
65 
80 

(76) 
48 
12 
40 
46 

(16) 


2-4X14 
2-4 X 8 

1-4X12 
1-4 X 14 
2-4X10 
2-4X12 
1-4X12 

4X10 
4X12 


188 
128 

19 
76 
98 
118 
157 
98 
24 
86 
93 
32 


MM MtOtOMM MtO 
II 1 1 1 1 1 II 

MM MMMMM MM 

00 OOOOO 00 
XX XXXXX XX 

MM MMMMM MM 

00 OOOOO loto 



The first-floor heat registers are all of the floor form. The 
register is omitted from room 3 owing to the small size. The 
heat for rooms 7 and 12 is divided between two registers, that 
in room 12 being made larger than necessary for this room. 
It is placed near the door of room 7 so that the heat enters 
that room. 

It will be seen in the table that 4X14^' is the Hmiting 
size of stacks. In the actual construction no vents were used 
extending to the attic. The table, however, is made to 
include these so as to illustrate the method. In Fig. 178 the 
position of registers and stacks is shown. The remaining 
computation is that for the cold-air supply and recirculated air 
supply. 

Of the air supply of 83,550 cu.ft. at 70° F. 30,000 enters as 
cold air at 0° as leakage and the full 80,000 passes back as 
recirculated air at 70°. The area of the circulating ducts using 
a low velocity of 4 ft. per second mil be 



a = 



80000 
4X3600 



— Ci 



si sq.ft. 



252 



ELEMENTS OF HEATING AND VENTILATION 



The register faces should be 



5^ 



_Ql 



0.66 



8t sq.ft. 



The house is planned to have one register under the stairs of 
6 sq.ft. connected to 4 sq.ft. of flue and one register of 3J ft. in 
the corner of room i, connected to a flue of 2 sq.ft. The cold 
air when needed enters as shown in Fig. 177. The area of 
the cold-air opening was 2| sq.ft. This, however, is rarely 
needed. 

The use ol the jib panel of a stairway as the place for the reg- 
ister of the recirculating flue is excellent. It is better than one in 
the hall floor in that it is not conspicuous and does not collect 
dirt, nor does it form an unpleasant place over which one must 

walk. The return duct must be 
of ample size and it must lead into 
the base of the heater by easy 
curves. 

In all cases the air supply must 
be ample if the heater is to per- 
form its duty. Had the 80,000 
cu.ft. been introduced from the 
outside, the area required would 
have been 




80000X0.87 
4X3600 



= 5 sq.ft. 



This air supply may be filtered 
by passing it through cheesecloth 
or by passing it over a series of 
baffles as shown in Fig. 179, the 



Fig. 179. — Baffle Screens. 

area of the various parts being sufficient for the passage of the 



air. 



Some designers proportion the cold-air duct by the total 
area of the leader pipes. This method can be used, but it is 
just as well to figure it from the amount of air to be handled. 



FURNACE HEATING 253 

The cold-air inlet should always be placed on the side toward 
the prevailing winds. 

The size of the hre pot is found at this point, although really 
belonging to the next chapter. From the heat to be developed 
as found in the first part of this chapter the total heat with the 
leakage air to be cared for is 144,000 B.t.u. per hour. If the 
efficiency of the furnace is taken at 60 per cent and the rate of 
burning coal is 4 lbs. per square foot, the area of the grate is 

144000X144 

^ = f. v^ '^ = 620 sq.m. 

0.60X14000X4 



Diam. = 28 



// 



This matter, with the size of the smoke flue, will be further con- 
sidered in the next chapter. In figuring the pipes, furnaces and 
other parts for a room, some designers and manufacturers reduce 
the heat quantity to equivalent glass surface while others find 
equivalent volume in cubic feet. 

Now Carpenter's approximate rule, 



H={tr-to) —^G + 0.027lV , 



4 

(p. 69) shows that 4 sq.ft. of wall is equivalent to i sq.ft. of 
glass and for one change of air per hour each 50 cu.ft. of volume 
is equal to i sq.ft. of glass. Hence if one-fourth of the wall 
area in square feet and one-fiftieth of the volume in cubic feet 
times the changes per hour are added to the glass area the result 
is called the equivalent glass area. In some methods the ven- 
tilation term is omitted and the floor and ceihng are added in 
giving the equivalent glass as equal to the glass plus one-quarter 
the waU^ area and one-twentieth of the area of the floor or 
ceihng to care for losses to basement or attic in first-floor or top- 
floor rooms. The equivalent is then multiphed by the heat loss 
per square foot of glass to find the total heat loss. This glass loss 
isabout 70 B.t.u. per square foot per hour. 

In one of the equivalent cubic feet methods the actual 



254 ELEMENTS OF HEATING AND VENTILATION 

cubic feet are increased by 75 cu.ft. for each square foot of 
glass surface and 8 cu.ft. for each square foot of wall space. 
This rule shows that the changes per hour are ij, and that the 
allowance for wall area is not nearly sufficient. 

In both of these methods allowance is made for exposure, 
10 per cent being added on the north and west sides. 

Certain manufacturers list pipes and heaters to care for 
equivalent cubic feet or square feet, and these may be used in 
designing. These methods are all equivalent to the theoretical 
one given in the text, but they are not as valuable, as the work 
is too empirical. 

The methods used in calculation for any form of building 
are similar to the above. 

When distant rooms are to be heated a combination system 
is sometimes used in which the distant rooms are heated by hot 
water furnished by a coil or cluster in the fire box of the furnace, 
as will be shown later. The method of determining the size 
of flow pipes, radiators and various parts of this system have 
been discussed in previous chapters. 



CHAPTER X 

FURNACES AND BOILERS 

The ordinary hot-air furnace, Fig. i8o (Graff Co.'s Lacka- 
wanna Furnace) consists of an ash pit, ^, a fire pot, B, a radiator 




Fig. i8o. — Graff Lackawanna Furnace. 



C and within the radiator the combustion chamber. The radiator 
may be made of sheet steel between cast heads as shown, or it 
may be of cast iron, Fig. i8i (Graff-Comfort Furnace). The 

255 



256 



ELEMENTS OF HEATING AND VENTILATION 



plan of radiator is illustrated in Fig. 182. The gases enter the 
dome over the combustion chamber, which contracts in the form 
of a dome and is connected to the center portion of the radiator. 
The hot gases thus pass around the radiator to the smoke 
outlet. In most cases there is a by-pass valve or cut-off plate 
which on being moved gives a free passage from the fire pot 




Fig. 181.— Graff Comfort Heater. 



to the smoke outlet to be used on starting fires. The base ring 
D of the furnace is placed on the brick foundation which in many 
cases forms the cold-air pit to which the air supply is brought 
from the atmosphere or house. A central pier is usually built 
to carry the weight of the ash pit, fire box and radiator. The 
grates are mostly made of triangular-shaped toothed bars, 
Fig. 183, supported on their ends and so arranged that by 
turning one of the bars of the grate, one-half of them turn, 



FURNACES AND BOILERS 

Clean Out 



257 




Smoke 

Outlet 

^Hard Coal) 



Feed 

Fig. 182. — Plan of Furnace Radiator. 




Fig. 183.— Grate and Ash Pit of Fuller, Warren & Co. 



258 



ELEMENTS OF HEATING AND VENTILATION 



cutting clinkers and allowing clinkers and ashes to fall. A gal- 
vanized-iron casing is now placed around the furnace and is 
carried up to the bonnet. This casing should be of bright iron 
to cut down the radiation loss and in some cases it is made double 
with an air space for this purpose. 

The air duct leading to the pit beneath the furnace is made 
of brick or concrete and is covered by wood or reinforced con- 
crete, Fig. 184. In case the concrete form is used manholes 
should be left for cleaning or examination. 




Fig. 184.— Cold-air Ducts. 



The main objection to the type of furnace shown in Figs. 
180, 181, which is probably the most common form, is the 
fact that the heating surface is not sufficiently large for the grate 
area. To increase the heating surface in their heater, the Grajff 
Co. in their " Faultless Furnace," use a number of air-heating 
flues, Fig. 185, which are surrounded by the hot gases and are 
exposed to the radiant heat and through which the air passes. 
The hot gases pass through openings at the top of these air-heat- 
ing flues to the exterior surface and, by means of the baffle 
plates, have a long path to the smoke outlet, giving up their 
heat to the walls of the boxes. The outside of this hot-^as 



FURNACES AND BOILERS 



259 




260 



ELEMENTS OF HEATING AND VENTILATION 



passage is made of sheet iron and this serves as the outer surface 
of the radiator. The casing is placed outside of this so that 




Fig. i86. — Kelsey Warm-air Generator. 




Fig. 187. — Tubes in Radiator, 



this furnace has much the same appearance as the Lackawanna 
furnace of this company. 



FURNACES AND BOILERS 261 

The fins guiding the air into the air-heating flues also add 
heating surface. 

The Kelsey warm-air generator or furnace, Fig. i86, shown 
with a hot-water generator at the top of the combustion chamber, 
is quite similar to the Graff furnace. In this the air-heating 
flues or elements are made corrugated to increase the heating 
surface. The action of this furnace is similar to that just 
examined. 

The same result may be accomplished partially by putting 
tubes through the hot gas space of the radiator, Fig. 187, and 
allowing the air to pass through the tubes while the gases pass 
around them. This method should improve the efficiency of 
the heater. This figure illustrates the method of putting the 
casing together and the bonnet. The three castings forming 
the ash pit, fire pot, and dome of fire box are clearly seen. These 
sections are fitted together by the edge of one casting fitting 
in a groove in the other, which joint is filled with a stove cement, 
making it tight. The same substance is used in putting the 
sections of the other furnaces together. It is important that 
this work be carefully done, as a leak of coal gas might poison 
the occupants of the house. The top of the furnace is often 
covered with sand to cut down the radiation from the top and 
a sand ring is placed at the edge of flat tops to hold this. 

Fig. 188 is the special Novelty Furnace of the Abram Cox 
Stove Co. in which the increased heating surface is obtained by 
complex castings of considerable length. The method of making 
gas-tight joints is illustrated as well as the use of a double 
casing. The direct draft for cutting down the resistance is shown 
near smoke outlet and the water pan near the bottom at B. The 
water pan should be installed on all hot-air furnaces to humidify 
the air, giving it the necessary amount of moisture. The pan 
should be located \yhere it will not be in contact with the hot 
air, as that air could take up so much moisture that this would 
be deposited on furniture and windows when cooled to the room 
temperature. It is usually placed near the bottom of the fur- 
nace where the air temperature and consequently the moisture 
content is not high. 



262 



ELEMENTS OF HEATING AND VENTILATION 



Sectional heaters or boilers, Fig. 189, are used for either 
hot water or steam. They are made of sections which may be 




Fig. 188. — Special Novelty Heater. 

increased in number to form heaters of different capacities. 
The middle sections are the same in form except for side or top 
outlets, while special shapes of sections form the rear and front. 
The sections are so made that there is a large amount of surface 



FURNACES AND BOILERS 



263 



exposed to the fire. This is done by having considerable space 
between the lower parts of the sections, although at the top the 




Fig, 189. — No, 5-15-6 Ideal Sectional Boiler. 



sections come so closely together that three passages are formed 
through which the gases must pass to the chimney. The 
sections of the boiler shown, the Ideal Sectional Boiler of the 



264 



ELEMENTS OF HEATING AMD VENTILATION 



American Radiator Co., are held together by bolts, the sec- 
tions being connected by three conical-faced push nipples. 
The sections A, Fig. 190, are supported by the casting forming 
the grate and ash pit. Some other boilers, as the American 
of the Pierce Co., B, Fig. 190, are made of sections which are con- 
nected by three manifolds, attached to flanged nipples screwed 
in at a, b and c. The Ideal Boiler has an outlet at the top and 
the bottom as shown in the figure for steam or water and 
feed. The steam boilers are usually provided with damper 
regulators which are attached as shown to the damper and 





Fig. 190. — Sections of Boiler. 

ash-pit door. They are operated by the pressure in the steam 
boiler and shut draft and ash-pit doors when the pressure 
rises, while at low pressures both are opened. Fig. 189 
shows the equipment on one of these used as a steam boiler. 
Fig. 195 illustrates the dimensional sheet of one type of this 
boiler, the table of which will be of service in laying out 
plans before lettng contracts. For small installations small 
circular boilers are used. Several of these are illustrated in 
Fig. 191. A represents the Pierce Boiler, in which the sec- 
tions are united by screwed nipples. The water leg on the 
side of the fire box forms a good heating surface. The outlet 
for steam (or water) is at the top, while the return enters at 
the bottom. 



FURNACES ANJD BOILERS 



265 






V 



o 



o 

pq 



266 



ELEMENTS OF HEATING AND VENTILATION 



The Spence water boiler, as shown at B, Fig. 191, consists 
of five cast circular sections attached to the base section by a 
cast manifold on one side. The manifold is so made that there 
is continuous circulation from the bottom to the top, in a definite 
path as shown by the arrows. C illustrates the Ideal Junior 
Water Heater of the American Radiator Co- used for heating 




' u n 



\i 



Fig. 192. — Humphrey Heater. 



water for laundry purposes or domestic service. This is not 
large and is intended to be used when a quantity of hot water 
is needed in the laundry or home. However, the gas heater 
has come into extensive use where hot water is needed for domestic 
service. There are a number of these heaters on the market. 
The Humphrey Gas Water Heater is shown in Fig. 192. The 
gas burners A are supplied through pipe B. The small pipe C 
supplies gas to the small pilot light D. The pilot light can be 



FURNACES AND BOILERS 



267 



shut off by the valve at the top of the Hne C and the main gas 
liae may be closed by a cock. 

The two water lines are behind the gas Hne. The cold water 
from the city supply or cool water from the storage tank enters 
at the bottom of the coils. The water circulates from the tank 
as soon as water is not taken from the faucets by an automatic 



Gas.to 
£ilot 




Fig. 193. — Rudd Heater and Tank. 



valve which allows cold city water to enter when a faucet is 
open. When the water from the tank reaches 140° F., a ther- 
mostat cuts off the gas supply except for the pilot light. As 
soon as cold water is used this thermostat turns on the gas 
supply. The Rudd Heater which is somewhat similar to this 
is also a good one to give an instantaneous supply of hot 



268 



ELEMENTS OF HEATING AND VENTILATION 



water. The demand for gas is so great in these heaters that 
special services are often run for them. Fig. 193 illustrates the 
attachment of one of these heaters to a storage tank with 
the thermostat attached to the gas supply at one end of 
the tank. 

For small plants where steel boilers are needed on account 
of a desire for high-pressure steam a locomotive type of small 
boiler, Fig. 194, may be employed. This is the Acme Boiler of 
the American Radiator Co., and they are built from about 10 to 
100 H.P. For large plants the water- tube or fire- tube boilers 
are used and these are considered in books on steam boilers 
and do not form a part of this work. For guidance of the student 




P'iG. 194. — Locomotive Type of Boiler. 



the following tables of a few standard furnaces and boilers are 
appended. Every engineer should have a supply of catalogues 
giving dimensions, sizes and capacities of various kinds of appa- 
ratus. The hot-air furnaces are rated by the cubic feet of volume, 
equivalent cubic feet or equivalent square feet of glass which the 
heater will care for. The hot-water and steam boilers are rated 
in square feet of radiation which the boiler will supply with 
heat. This includes the square feet of surface in radiators and 
piping combined. The numbers are the result of tests and in the 
catalogue of the American Radiator Company, they are found 
by taking four times the steam produced by the boiler per 
hour on a test in which the fire box has to be charged once 



FURNACES AND BOILERS 



269 



in eight hours. The allowance for piping should be made 
even though the pipes be covered. The piping in the ordi- 
nary direct system for steam amounts to about 25 per cent 
of the radiator surface, while in hot-water work the amount 
is from 30 to 50 per cent. 

DIMENSIONS AND CAPACITY OF SPECIAL NOVELTY HEATERS 





Capacity in 


















"Equivalent 


















Cubic Feet" 


















Heater will 
Heat, on the 


Height of 


Diameter 


Diameter 


Height 


Diame- 


Weight, 


Size of 
Cold-air 




Basis of Main- 


Heater 


of Fire- 


of 


to Top of 


ter of 




Duct 


i^o. 


taining a Tem- 


Cased 


pot, 




Radia- 


Smoke 




Re- 




perature of 70° 


Complete. 






tor, 


Pipe, 








Above Zero in 


Inches. 






Inches. 


Inches. 




ne es. 




the Building 


















when the Out- 


















side Tempera- 


















ture is Zero.* 
















732 


32000 


62 


19 


32 


50 


7 


820 


10X20 


736 


41000 


64 


21 


36 


52 


8 


1060 


12X20 


740 


50000 


65 


23 


40 


53 


8 


1280 


12X26 


744 


61000 


66 


26 


44 


56 


9 


1675 


12X32 


748 


73000 


67 


28 


48 


57 


9 


2125 


14X32 


752 


76000 


68 


28 


52 


58 


9 


2270 


14X33 


756 ' 105000 


70 


32 


56 


60 


9 


2850 


14X48 



*For definition of "Equivalent Cubic Feet" see p. 254. 

DIMENSIONS AND HEATING CAPACITY OF FULLER, WARREN & 
CO.'S B SERIES FURNACES 

(Similar to Fig. 180 but with steel radiator). 



Size. 


Diameter 
Firepot, 
Inches. 


Diameter 
Casing. 
Inches. 


Height 

Furnace, 

Inches. 


Recom- 
mended 
Size of Air 
Box. 


Diameter 
Smoke 
Pipes. 
Inches. 


Number 
of Aver- 
age Size 
Hot-air 
Pipes. 


Diameter 
of Single 

Hot-air 
Pipe. 

Inches, 


B 18-32 


18 


32 


46f 


10X15 


7 


3 to 4 


20 


B 20-36 


20 


36 


5oi 


10X22 


7 


4 to 5 


22 


B 22-42 


22 


42 


51I 


12X25 


8 


5 to 7 


26 


B 24-48 


24 


48 


54i 


13X28 


8 


6 to 8 


28 


B 26-53 


26 


53 


56i 


14X32 


8 


7 to 9 


30 


B 28-58 


28 


58 


58f 


14X35 


10 


9 to II 


32 


B 31-60 


31 


60 


59f 


14X45 


10 


II to 12 


36 


B 36-65 


35 


65 


61 


16X42 


10 


12 to 15 


40 



270 



ELEMENTS OF HEATING AND VENTILATION 



DIMENSIONS AND HEATING CAPACITIES, GRAFF FAULTLESS 

HEATER 



Size. 


Diam. 
Firepot 


Diam. 
Casing. 


Height, 
Casing. 


Height 
with 
Cone 
Top 

Casing. 


Grate 
Area, 
Sq.ins. 


No. of 
Flues. 


Heat- 
ing 
Sur- 
face. 
Sq.ft. 


Usual 

Cold 

Air 

Duct, 


Cubic Feet 
Capacity. 




Houses \ Halls 


19-48 


19 


48 


48 


66 


283 


9 


131 


12X36 


15000} 25000 


22-54 


22 


54 


54 


69 


380 


10 


152 


14X40 


25000; 45000 


25-60 


25 


60 


60 


70 


491 


II 


176 


14X48 


40000 1 60000 


30-70 


30 


70 


70 


70 


707 


12 


219 


16X60 


60000 ! 1 00000 



DIMENSIONS AND HEATING CAPACITIES- 
GENERATORS 



-KELSEY WARM-AIR 









Regular 








Square 


Size 


Diameter 


Height of 


Height 
Generator. 


Diameter 


Area of 
Grate 


Heating 
Surface 


Feet 
Heating 


Genera- 


of Base, 


Castings, 




Grate. 






Surface to 


tor. 


Inches. 


Inches. 


plete. 
Inches. 


Inches. 


Feet. 


Feet. 


Each Square 

Foot of 
Grate Area. 


24 


56 


59 


69 


24 


3 


161 


51 


27 


60 


60 


72 


27 


4 


176 


44 


30 


64 


64 


76 


30 


5 


211 


43 



Size 
Genera- 
tor. 


Free Area 
Square 
Feet. 


Cubic 
Feet Air 
Heated 

per 
Minute 
Mechan- 
ical. 


Cubic Feet 

Air Heated 

per Minute 

Gravity. 


Thickness 
of Brick 
Walls, 
Heater 
Case. 
Inches. 


Inside 
Dimen- 
sions, 
Brick 
Housing 

One 

Heater. 

; Inches. 


! 

Size of Weight with 
bmoke 1 Cast 
Pipe. i Casing. 
Inches. | 


24 
27 
30 


4 
5 
6 


2800 
3500 
4100 


1900 
2300 
2900 


8 ■ 54X68 
8 ' 57X70 
8 60X72 


9 i 2520 
9 ' 2975 
9 , 3425 



The ratings in the following table for boilers are for hard 
coal. With soft coal use one size larger than tabular value. 
Ratings include all pipes, covered or uncovered. These amount 
to about 30 per cent of radiator surface. The width of the 
grate is equal to the number of the boiler; 15, 22, 28, 36 and 48 
represent the grate width. The length is the length of the 
fire box. 



FURNACES AND BOILERS 



271 



LEADING DIMENSIONS, IDE.\L HEATERS FOR STEAM AND 
HOT WATER 



Num- 




Height. 


1 Width. 










Square Feet 


ber and 
Sec- 
tions. 


Length, 
Total. 


Total. 


1 Total. 


Water 
Line. 


Firepot 


Out- 
let. 
Ins. 


Smoke 
Pipe. 


Capacity. 


Steam 


1 
Water Steam Water 

1 ! 


Steam. 


Water. 


15-4 


40I 


6i| 


42I 


: 38f 


27I 


38i 


19X18 


2-3 


8 


300 


500 


1 5-5 


47i 


6i| 


42i 


38! 


27I 


38i 


19X25 


2-3 


8 


425 


700 


15-6 


53f 


6i| 


42h 


381 


27* 


381 


19X31 


2-3 


8 


550 


900 


22-5 


53i 


67i 


52i 


45i 


36 


45 


25X28 


2-4 


10 


800 


1300 


22-6 


6oi 


67i 


52i 


45i 


36 


45 


25X35 


2-4 


10 


1000 


1650 


22-7 


67i 


67i 


521 


45i 


36 


45 


25X42 


3-4 


10 


1200 


2000 


22-8- 


' 74i 


67i 


52i 


45i 


36 


45 


25X49 


3-4 


10 


1400 


2350 


28-5 


60 


75f 


6of 


53l 


44 


52 


33X32 


2-4 


12 


1300 


2150 


28-6 


68 


75f 


6of 


53* 


44 


52 


33X40 


2-4 


12 


1625 


2675 


28-7 


76 


75f 


6of 


53l 


44 


52 


33X48 


3-4 


12 


1950 


3200 


28-8 


84 


75f 


6of 


53* 


44 


52 


33X56 


3-4 


12 


2275 


3725 


.36-S 


69f 


83 


70 


64 


53i 


60 


41X36 


2-5 


15 


2100 


3450 


36-6 


78I 


83 


70 


64 


53i 


60 


41X45 


2-5 


15 


2625 


4325 


36-7 


88 


83 


70 


64 


53i- 


60 


41X54 


3-5 


15 


3150 


5200 


36-8 


97i 


S3 


70 


64 


53i 


60 


41X63 


3-5 


15 


3675 


6050 


36-9 


io6i 


83 


70 


64 


53i 


60 


41X73 


4-5 


15 


4200 


6925 


48-6 


92 


97 


8if 


80 


68 


70 


50X53 


2-6 


21 


4750 


7825 


48-7 


102I 


97 


8if 


80 


68 


70 


50X64 


2-6 


21 


5700 


9400 


48-8 


114 


97 


8if 


80 


68 


70 


50X75 


3-6 


21 


6650 


10975 


48-9 


I24i 


97 


8if 


80 


68 


70 


50X86 


3-6 


21 


7600 


12550 


48-10 


135 


97 


8if 


80 


68 


70 


50X90 


3-6 


21 


8550 


14125 



The dimensions in this and the following table w^iU be found 
to be approximately the same for other makes of sectional boilers 
and for that reason no other tables will be given. 

In finding the size of a hot-air furnace one method is to find 
the amount of heat for the heat loss and for the heating of 
the ventilating air up to 70° and to di^dde this by the 
product of the efficiency of the furnace and the heating value 
of the coal and the result is the amount of coal required 
per hour. This is then divided by the rate of combustion, 
pounds of coal per square foot per hour, to find the area of the 
grate. 



272 ELEMENTS OF HEATING AND VENTILATION 

-X- 




FiG. 195. — Dimensional Views of Sectional Boiler. 



DIMENSIONS OF IDEAL BOILERS OF THE AMERICAN 
RADIATOR CO. 



Size. 


A 


B 


C 


Z) 


£ 


F 


G 


H 


15" boilers.. . 


28I 


46^ 


131^ 


41I 


34f 


I2i 


i8f 


25 


22" '' ... 


36i 


52i 


15I 


47f 


40I 


i4i 


2li 


28I 


28" '' ... 


44I 


6of 


i8| 


55l 


46i 


16 


24 


32 


36" " ... 


54l 


69i 


21H 


63I 


521^ 


i8i 


27f 


36i 


48" " ... 


69 


8if 


27i 


73i 


59i 


21* 


32i 


43 



Size. 


I 


/ 


K 


N 





P 


5 


r 


15" boilers.. . 


161^ 


23f 


8X14 


iif 


6i 


8 


i3i 


7i 


22" " ... 


i6f 


29i 


8X14 


9* 


7l 


10 


14* 


8§ 


28" '* ... 


17I 


37l 


9X18 


10 


8 


12 


16 


9l 


36" '' ... 


181^ 


451^ 


10X20 


loM 


9i 


15 


183^ 


io| 


48" *' ... 


22f 


58I 


11X19 


14H 


lof 


21 


I7f 


I2| 



For X, Z/, and M see previous table. 

If ^ = heat loss per hour; 

Fz = leakage air in cubic feet at 70° per hour; 
tr = room temperature; 



FURNACES AND BOILERS 273 

/o = outside area; 

A = heat per pound of coal in B.t.u.; 
eff.= efficiency of furnace = 65 per cent; 
= rate of combustion = 4 or 5 lbs.; 
A =area of grate. 



H-\-0.02Vi{tr-to) 

efi.XhXO 



(159) 



This area should be compared with the area of the manufac- 
turer's heater for the same volume of building. The results 
should be approximately the same. 

For some large buildings the area will be found to be greater 
than the amount to be obtained from the largest heater. In 
that case two or more heaters must be used. These may be 
placed at convenient locations in the cellar, thus shortening 
runs and making the heating more positive if it is possible to 
have proper chimneys, although in some cases twin furnaces or 
batteries have to be used. In this method several furnaces are 
placed side by side and a common bonnet is used connecting 
all casings (Fig. 176). This of course has the advantage over 
the separate arrangement of allowing one to run a single furnace 
at full capacity when a small amount of heat is needed in the 
early or late heating season. 

The application of this method to the residence of Chap. 
V gives the following area: 

I St. From heat required : 



Total heat = 144000; 

^ 144000 

Grate area = ^ , , —— = 620 sq.m. 

0.60X14000X4 

Diam. grate = 28 ins. 

2d. By method of volume: 

Total volume = 27600 cu.ft.; use 25-60 Graff. 
Diam. grate 25 ins. (Graff table). 



274 ELEMENTS OF HEATING AND VENTILATION 

3d. By method of equivalent volumes: 



Room. 


75 X Glass. 


8 X Wall. 


Volume. 


Total Equivalent 
Volume 


I 


9,100 


2,250 


3,110 


14,460 


2 


8,000 


2,700 


2,160 


12,860 


3 


2,100 


750 


400 


3,250 


4 


2,600 


1,540 


1,390 


5,530 


5 


3,600 


1,550 


1,620 


6,770 


6 


5,850 


620 


2,110 


8,580 


7 


6,400 


2,400 


2,910 


11,710 


8 


3,600 


1,680 


2,000 


7,280 


9 


750 


390 


720 


1,860 


10 


3,150 


1,520 


1,700 


6,370 


II 


3,150 


1,620 


1,710 


6,480 


12 


1,650 


300 


480 


2,430 


Total 


49,950 


17,320 


20,310 


87,580 





This requires a No. 752 Special Novelty Heater with 28-in. fire pot. 

In selecting a furnace the endeavor should be made to get 
as much heating surface per square foot of grate surface as pos- 
sible. There are certain furnace books which state that unless 
the galvanizing is burned off of the smoke pipe the furnace has 
not been operated to its full capacity. This burning means 
a high temperature of the exhaust gases and hence a great loss 
in them. There should be enough surface to remove the heat 
before these gases leave the furnace. The flue will be hot in the 
coldest weather, but this is no proof that the furnace is working 
properly. The furnace giving the lowest temperature of exhaust 
gases, other things being equal, is always the best furnace. The 
Kelsey and Graff furnaces give ratios of heating surface to grate 
surface of 45 : i, and the student should have this in mind as 
a possible ratio. In steam-boiler work 35 to 40 is the value 
often used. 

The flue leading from the furnace to the chimney is usually 
fixed by the size of the fire pot or the capacity of the furnace. 
An area of one-twelfth of the grate for furnaces and one-eighth 
of the grate area for small boilers may be used, although the 
method employed by many manufacturers is to use a table 
which gives the B.t.u. cared for by various sizes of flue. 

The chimney should be at least 30 to 40 ft. high and the chim- 



FUENACES AND BOILERS 275 

ney flue if round should be 2 ins. larger in diameter than the 
smoke pipe, while if square the size of the square is i J ins. larger 
than the diameter of the smoke pipe or flue. If the chimney 
flue is rectangular the dimensions h and d should be such that 

hd ^ ' ^ c r ^ • ^ ' 

^TT— — ^ = or >T side of square of desired size. 

2{b+d) 

The inside of the flue should be as smooth as possible and 
tight. It is well to line it with tile for fire protection, the space 
between tile and brick being filled with mortar. This chimney 
can then be built of 4-in. brick work, while an unlined flue must 
be made of 8-in. brick work. The top of the chimney must pass 
above the highest part of the building. The smoke flue must 
not extend beyond the inner surface of the chimney flue. It is 
well to have a pocket at the bottom of the chimney with a 
clean-out door to remove soot when necessary. 

In figuring the size of the boiler to be used for a steam or 
hot-water installation the amount of heat required is reduced 
to pounds of coal by a method used above, taking the efficiency 
at 66 per cent. The rate of combustion may be taken as 5 to 8 
lbs. of coal per square foot per hour. This gives the area of the 
grate, and from a table the size of boiler may be found. 

Another way as mentioned above is to compute the surface of 
the radiation and pipes and then select size from a catalogue. 
These methods are now applied to the residence for a steam 
boiler and after that for a hot-water boiler. 

For the steam system of the residence the total amount of 
radiation is 624 sq.ft., and the piping amounts to about 150 
sq.ft., giving a total of 774 sq.ft. This requires a 22-in. 
5-section Ideal Sectional Boiler. Computing this from the size 
of the grate surface the following results: 

Total heat supply = 188500; 

188500 

Grate area = —^y— = 4. sa.it 

14000 X. 66X5 



Using 22 ins. width, 
Length 



4X144 

22 



276 ELEMENTS OF HEATING AND VENTILATION 

The grate surface of a 22-5 boiler is 22'' X 28'^ This method 
gi\)'es the same result. For the hot- water equipment the amount 
of heating surface is 1009 sq.ft. with 150 sq.ft. of pipe surface. 
The total surface is 11 59 sq.ft., requiring the same size of 
boiler as before. 

The table on page 272 gives the leading dimensions of this 
boiler. 

The flue of the chimney for the boiler is now determined 
from the builder's table or else as one-eighth of the grate area. 
The sam-e remarks apply here as to chimneys and flues of hot- 
air furnaces. 

The flue in this case is to have an area of 

^ =1X4X144 = 72 sq.in. or 6? = 10 ins. 

This is the value given in table. 

The boiler should be set on a foundation which forms the 
bottom of the ash pit. This is made of concrete. After the 
boiler is connected and tested it should be covered with at least 
two inches of asbestos or magnesia plaster. 

The furnaces and boilers should be provided with the neces- 
sary gauges, shovels, pokers, cleaners and brushes or scrapers. 

The question of the relative merits of the various systems 
is one which is difflcult to decide, and one about which the various 
manufacturers are usually prejudiced. As far as efflciency is con- 
cerned, if the proper amount of heating surface is used, the systems 
are all equally good. If the loss in the chimney gases amount 
to 35 per cent, due to the unburned gases, dilution, hot gas or 
any other cause, 65 per cent of the heat of the coal must 
be used in the house somewhere. From 60 to 65 per cent is 
obtained with all furnaces or boilers if properly designed, and 
even better results if the fire is operated steadily. The great 
trouble with most hot-air furnace work and the one which is 
the cause of hot water and steam showing better results, is the 
fact that the furnace does not contain sufficient heating surface. 
It is not the fact that a given furnace will heat a house which 
should count, but that it will do it without a great loss of heat 



FURNACES AND BOILERS 277 

to the chimney. The same result would happen, although it 
is not so common, when the boiler is much too small for an 
installation. ^ 

As far as convenience in installing is concerned without the 
use of valuable space the hot-air methods using furnace or indirect 
radiators are better than the direct systems, which take valuable 
space. The indirect system is better than the furnace system for 
large buildings, as the heating coils may be placed under the stack 
carrying the air, or air under pressure is used, while the furnace 
gives such a small driving pressure that there is difficulty in 
getting the proper flow on long lines. 

The hot-air methods will supply air for ventilation, and this 
air can be brought in at the proper humidity. The direct-steam 
or hot- water system does not permit of ventilation, and when 
needed with this system, tempered air must be brought in by 
use of a fan blower and coil. 

The hot-air furnace systems are out of the question for 
large buildings, as the circulation is not possible. The direct 
system is suitable in that the piping is easy to run and does 
not take much space. 

The indirect system of heating requires the operation of a 
steam engine or electric motor and large air ducts and unless 
ventilation is necessary the direct systems are easier and more 
cheaply installed. In residences and office buildings where 
there are not many occupants in the various rooms, this method 
is quite extensively used. The method is positive even to the 
remotest parts. 

Steam systems are usually cheaper than hot-water systems, 
because less surface is required owing to the greater unit value 
of the steam surface. The steam may be raised more quickly 
than the hot water, but unfortunately it drops more quickly 
also. 

A hot-water system gives a more uniform temperature over 
a long period. It is not subject to sudden changes, and the 
radiators are at a lower temperature. It consumes time in bring- 
ing the house to a proper temperature after the house has been 
chilled. 



278 ELEMENTS OF HEATING AND VENTILATION 

The radiators in these two systems take valuable space, 
while if concealed they are difficult to repair. 

As far as cost of installation is concerned the hot-air fur- 
nace system is the cheapest; then follow direct steam, direct 
hot water, indirect steam and indirect hot water. The furnace 
system for a dwelling house costs about one-half to two-thirds 
the cost of a steam system. 



CHAPTER XI 

DISTRICT HEATING 

District heating or heating from a central station has been 
used for a long time in institutions where a number of buildings 
are within the radius of several hundred feet, and this same 
method has been extended to heat towns or portions of towns 
when the remote buildings have been several miles from the 
power house. 

There are two general methods: hot water and s:2am. In 
the hot-water system a complete circuit is usually made with 
a pump to force the water through the feed-water heater into 
the supply main, from which the water passes into the buildings 
through a service or branch pipe and after passing through 
the radiators it leaves through a service and enters the return 
pipe, passing back to a discharge tank and thence to the pump. 
The heater may be an ordinary boiler using hot gases to heat 
the water, or a feed-water heater using steam or hot gases from 
a boiler to heat the water. Any form of heater may be used. 

In the steam system, live steam from boilers or exhaust 
from engines passes through the supply main and service pipes 
to the buildings and in some cases the returns from the buildings 
are carried back to the power house, while in other cases this 
water of condensation is sent to the sewer. 

In the hot-water system there is no reason why the pipe should 
be laid on a definite grade. It may follow the contour of the 
surface of the ground through which it passes. In this system 
when closed there is no power consumed in raising water to the 
tops of tall buildings, as the down legs will balance the weight 
of the up legs. In fact there is really some motive power due 
to the greater weight of cold water in the down legs. The water 
may be measured by meter and if the temperatures of inlet and 

'279 



280 ELEMENTS OF HEATING AND VENTILATION 

outlet are known the heat used by a building is determined. 
This latter factor is the difficult one to find at the con- 
sumer's building in a hot- water district system during the whole 
season. 

The hot water may be stored in times of peak load if the 
system uses exhaust steam to heat the water and this water 
may be used in time of small steam load on the engines. 

In the steam system, the steam and return mains must be 
put on a definite grade if the mains are to be dripped and all 
drips and condensation are to be returned to the power house. 
This grade may mean considerable cutting to accommodate 
the contour of the ground surface, or if this is not done all low 
spots must be drained and a pump used to return the drips and 
condensation. These two reasons have resulted, in many cases, 
of employing a single pipe in steam systems allowing all drips 
and condensations to pass into the sewer. To cut down the loss 
of heat in such cases, the drips from the low points of the line 
are taken into a customer's property and passed through a tem- 
pering coil so as to heat some of the ventilating air of the building. 
The same method is used with the condensation of the building 
and thus the water is discharged into the sewer at a very low 
temperature. In this system much of^ the exhaust steam at 
peak load must be wasted unless live steam is largely used for 
the heating plant at small loads and thus the advantages of the 
use of the heating plant as a by-product plant are not attained. 
In many cases where boilers are used for heating, the exhaust of 
engines at certain times is used to do part of it, as in an office 
building, but in a true district-heating system there is generally 
a waste of steam at peak engine load when exhaust steam is 
used. 

The steam system in most cases dispenses with the use of 
the distributing pump, as 5 or 6 lbs. back pressure will carry the 
steam a considerable distance. 

The pipes in a district system are installed so as to properly 
drain, so that expansion is cared for and so that the heat losses 
may be reduced to a minimum. 

To properly drain the pipes a uniform grade must be estab- 



DISTRICT HEATING 



281 



lished, or high and low points are fixed and the pipe grade is 
suited to these. The >^ 



low points are usually 
placed at manholes 
so that traps may be 

placed there which are • — 

accessible for adjust- 
ment or repair for 
steam systems or so that drains 
may lead to the sewer in water 
systems. Drainage is important, 
as corrosion and rusting are the 
main troubles in district systems. 
It is claimed by advocates of the 
steam system that the pipes will 
not corrode as rapidly with steam 
as they will when hot water is used. 
The rusting out of pipes is one 
important objection to this system. 

The expansion is cared for by 
swinging ells, by slip expansion 
joints, by pipe bends, by corrugated 
pipes or by a special contrivance 
known as a variator. These are 
shown in Fig. 196. They are all 
of value. The slip expansion joint 
is objectionable in that the leakage 
from the packing is hard to care 
for and at times the sleeve becomes 
incrusted so that it does not slip 
easily. The swinging ells, although 
efi&cient in caring for expansion, 
have a large amount of resistance, 
and this is objectionable. 

The corrugated pipe section is 
one which offers little resistance 
and allows the expansion to take 



P^ 




Fig. 196. — Arrangements for 
Expansion. 



282 



ELEMENTS OF HEATING AND VENTILATION 



place easily. The same may be said of the pipe bend, on 
account of the large radius of the bend. 

The variator has a flexible diaphragm to make the move- 
able joint steam tight. When used it is provided with outlets- 
at top and bottom so that service pipes and drip pipes can be 
run from this point as the main casting is anchored and does 
not move. The variator shown is a single one in which the expan- 
sion occurs in one side. Double 
variators permit the pipes on. 
each side to move relative to the 
casing. 

To care for the radiation loss- 
several methods are used. In 
some cases pipes are covered 
with pipe covering, while in 
other cases the pipe is buried 
in a wooden box and surrounded 
by shavings, or the pipe may be 
placed in a wooden pipe made 
up of thick staves joined to- 
gether. 

The pipe covering is used 
when the pipe is carried in tun- 
nels, Fig. 197, or in certain forms 
of conduits, Fig. 198. Tunnels 
are so expensive to construct 
that they are rarely used except 
between buildings of a manufac- 
turing plant where steam mains 
are carried from a central plant to a group of buildings, or 
in a district system where a number of branch mains are carried 
from the power house to a point from which the lines radiate. 
The tunnel should be made sufficiently large for men to walk 
through and to care for the pipe hnes. The clear passageway 
outside of the standards should be at least 24 ins. wide and si 
or 6 ft. high. The crowded or small tunnel may be right for 
the original installation when the pipes and tunnel are cold;. 




Fig. 197. — Tunnel. 



DISTRICT HEATING 283 

although even then work is difficult, but when a broken or leaky 
main needs repairing, work is almost impossible on account of 
the heat. Brick arches are used for the roofs of tunnels, beams 
may be used with flat brick arches or reinforced concrete may be 
employed. The walls should be 12 ins. thick. The floor of 
all tunnels should drain to one side and the gutter should drain 
to proper sumps or sewers so that no water will remain on the 
floor. Water is not only hard on workmen, but the dampness 
is likely to cause the covering to mildew and rot. 

The pipe supports are made by fastening i J- or 2 -in. pipes 
into the floor and roof and . then using a pair of strap irons 
clamped into position by bolts. In 
this w^ay any ahgnment may be had 
with ease. 

The arrangement of underground 
conduits as shown in Fig. 198 with 
pipe covering around the pipe gives 
a very satisfactory construction. Split 
tile or gutter tile are made of regular 
terra cotta and are manufactured 
with a cut from the inside surface fig. 198.— Split-tile Conduit. 
almost to the outside, so that on 

striking them they break into two parts. One-half is then placed 
in the trench and well rammed into position for ahgnment and 
level, with the joints between the lengths of tile made up with 
mortar of one part cement and three parts sharp sand. The pipe 
is supported at 10- or 12-ft. intervals in one of several ways. A 
simple m^ethod of support is to place a piece of pipe across the tile 
in grooves after cutting them in the side of the tile so that the 
steam pipes are at the proper level in the conduit. After the cover 
is put on at this section concrete of one part cement, three parts 
sharp sand and six parts broken stone of 2 ins. size is placed 
around this section, filling a hole about 15 ins. long in the direction 
of the pipe and extending out about 10 or 12 ins. and reaching 
the full height of the tile. This is shown in Fig. 199. Another 
method is to use concrete sections at the proper distance 
apart in which rollers or rods as shown in Fig. 199, are used 




284 



ELEMENTS OF HEATING AND VENTILATION 



to carry the pipe. For conduit work, the pipe should have 
screw connections, as flange connections leak. After the pipe 
is installed it should be tested with water pressure to a 
pressure a Httle above that to be carried, and if found tight, the 
covering is placed around the pipe, the top half of the spHt tile 
put on and joints cemented. Then the ditch is back filled, care 
being taken to ram or tamp the earth. At times the earth is 
puddled with water during filKng to make the earth pack properly. 
This tile is usually water-tight if all joints at sides and ends 
are properly cemented together, but at times it is well to drain 
the conduit by placing crushed stone beneath it and placing an 
unglazed tile at the center of the stone to give a waterway for 




Fig. 199. — Supports for Pipes in Conduits. 



the seepage. This tile of course leads to a sump or sewer. This 
is necessary in some cases to keep the water from working into 
the conduit. Of course as shown in the figure any water reaching 
the conduit would flow along the bottom to the manhole. Figs. 
197, 198 illustrate installations where the return is brought back 
to the power-house, while Figs. 200-203 show systems when 
there is no return. 

Manholes should be placed at intervals, especially at branches, 
and by making the floor at a lower level, the seepage water 
collects here and may be removed. Fig. 200 shows the sections 
of manholes. The tops of these should be made as tight as 
possible with a double cover to cut down radiation losses. 

At times the insulating material, consisting of loose asbestos 
or magnesia, is filled into the conduit around the pipe, and in that 



DISTRICT HEATING 



285 



case no water should be allowed to enter. Figs. 201, 202 and 203 
show various methods of carrying single pipes. In Fig. 201 a 
wooden box is made up with air spaces. These spaces are filled 
with some substance to break up the air currents. The pipe is sur- 
rounded by some filler to stop air circulation and the whole box is 
covered with pitch. In Fig. 202 the box is made of concrete and 




Fig. 200. — American District System. 

in Fig. 203 the pipe is surrounded by a wooden covering and the 
whole is surrounded by concrete. In the last three methods the 
pipe is carried by some form of roller. Fig. 200 shows the method 
used by the American District Steam Co. The pipe or casing, 
Fig. 204j is made of wood staves 4 ins. thick locked together 
by tongues, wrapped with wire and lined with tin. The pipe has 
an air space of i in. between the tin and the sheet asbestos which 
is placed around the pipe. The staves are treated with creosote 



286 



ELEMENTS OF HEATING AND VENTILATION 



after shaping and after banding with a spiral of -fe in. galvanized 
wire embedded into the wood. A 3|-in. bell and spigot is formed 
at the end by turning after the pipe is made. The exterior 
is then treated with asphaltum, pitch and sawdust. 




Fig. 20I. — ^Wooden Conduit. 



The American District Steam Co. install their apparatus 
as shown in Fig. 200, using manholes at all special fittings such 
as variators (see Fig. 196) or at anchor specials. These anchor 




Fig. 202. — Concrete Condmt. 



specials are usually tees or crosses which supply the service con- 
nections. The variators also are points for connecting service 
mains or drips, as the main body is always so anchored that it 



DISTEICT HEATING 



287 



is a fixed point. The variators care for 50 ft. of pipe so that 
double variators are 100 ft. apart with an anchor special between 
them. In this way outlets may be made at 50-ft. intervals. 
The third manhole is used to control certain sections of the pipe. 




Fig. 203.— Wooden Condiiit in Ccncrete. 

In laying out a district system the map of the buildings 
to be supplied by a plant should be laid out and then the profile 
of the hne made, giving the cuts at the various points. In many 
cases these lines may be placed in alleys or small streets parallel 
to the main streets, in which the pavement is not so expensive 




Fig, 204. — Wooden Covering. 

and which will not interfere with traffic during construction or 
repairs. 

The steam or water used by the various buildings is then 
found and allowance is made for future growth and extension, 
and then the pressure to be expected at the various points 



288 



ELEMENTS OF HEATING AND VENTILATION 



IS assumed. By starting at the dead ends of the mains and work- 
ing toward the source, the amount of steam or water and the 
pressure drop on any hne are known. From this the size of the 
pipe may be found for the assumed pressures. 

There is a heat loss from the pipe Kne due to radiation, but 
in pipes lying buried in conduits surrounded by earth this quan- 
tity is much smaller than in pipes carried in a room. Experiment 
seems to indicate a formula for the heat per hour in the form 



H = RXsq.it. of external pipe surface. 



(i6o) 

























K 0.15 lb. 
g'lSOB.T.U. 

1 




















/ 


















/ 


/ 


^ 0.10 lb. 
















/ 


/ 




6- 100 B.T.U. 
m 

1 














/ 


/ 






t3 

% 

*Z 0.05 lb. 
o 50 B.T.U. 












/ 


/ 
















-^ 

















"^ 


















ti 


)0° 


15 


0° 


2( 


)0° 


2c 


0° 


a 


X)^ 


m 



lemp.of "Fluid in.Pipe 



R depends on the steam temperature and is given by the curve 
shown in" Fig. 205. This curve has been constructed from 
various experimental results. It is given in pounds of steam 
condensed per square foot per hour or in B.t.u. per hour. 
The value of 0.03 lbs. per hr. is, used for water and 0.05 for 5 
lbs. steam. The constant R may vary considerably, increasing 
as the covering becomes old or water-soaked. 



DISTKICT HEATING 289 

Some authors consider a loss due to friction, but this is not 
a loss, as the heat produced by this friction remains in the steam 
and although the pressure may drop there is no diminution 
of heat outside of radiation. 

This method of assuming pressures will not give the best 
size necessarily, unless the assumed pressure drop from the plant 
to the end of the line is the maximum possible amount. In 
that case the pipe is the best size, but when the pressure can be 
changed a smaller pipe mth more drop might be more economical. 
This problem, of economical size of pipe divides itself into two 
problems, one for water and one for steam. 

In the case of the hot-water system it is well to determine 
the cost of instalHng a certain size of main and then the cost 
of pumping the water through the main and the heat loss from 
it. After this is done a larger pipe is taken and in this the cost 
of pumping will be less, due to the lower velocity, but the instal- 
lation will cost more and there will be a greater radiation 
loss. If the sum of the cost of pumping, of radiation and of 
interest, depreciation and taxes be less for the large pipe than 
for the smaller one, the large pipe should be used. If, however, 
the interest, taxes and insurance, radiation and pumping cost 
more than the sum of these quantities for the small pipe, the 
latter should be used in preference to the larger pipe, and more- 
over it would pay to investigate a still smaller pipe. In this 
way one size is found which gives the most economical result. 
As an example suppose 100,000 lbs. of water is to be carried 
per hour to a building 3000 ft. from the power house at 170° 
and returned at 140° F. The size of the main is required. 

I St. Suppose the pressure fall is fixed at 10 lbs. per square 

inch^and this can and should be used. This permits of one 

answer only, and assuming a 4-lb. drop in the building, 6 lbs. may 

6X144 
be used; 6 lbs. per square inch is equivalent to — — ^ = 14.1 

ft. of water at 155° F. (at the mean temperature). 

^ I 00000 

Q.^TT7T~Z7l ^ = 0.45 cu.ft. per sec. 

^ 60X60X61.08 -^ ^ 



290 ELEMENTS OF HEATING AND VENTILATION 

The formula to be used to determine the quantity depends 
on that used to determine the friction head. The formulae 
mentioned in Chapter VII are not considered, as the loss in 
district systems is so great that more accurate methods must 
he employed. The approximate formula of Chapter VII was 
sufficient, as the runs were short in that work. The formula 
from the work of Williams and Haven as given by I. N. Evans is 

^1-85 
^ = 0.00035/ ^Y^J^^ (161) 

while the formula 

f^=flTg' (^6.) 

which has been used for so many years, has a constant term f 
which depends on the v and d. The tabular values of / which 
have been used indicate approximately 



f^lM ('^3) 

Using this the formula becomes 

^1-875 
^ = 0.0004/ -^^T^ (164) 

^1-875 /)l-875 r)l-875 

h = 0.0004/ -^^ = 0.0004 /x 1.875^5 = 0.0006/ ^^Tq^, 



d '" 



h I 



For the problem 



, /o.ooo6x6oooXo.4S^"^^^ \i 
d=[ — j =0.57 = 7 m. 



DISTRICT HEATING 291 

2d. Suppose the pressure is not limited and it is desired to 
know whether a 6-in. or 8-in. pipe would be better than a 7 in., 
supposing I H.P. hr. is worth i| cts. to this company. 



0.45 
Velocity in 6-in. line = — — = 2.2 ft. per second; 



0.45 
Velocity m 7-m. lme = — 7- = 1.7 ft. per second; 



0.45 

Velocity in 8-in. line = = 1.^ ft. per second; 

^ 0.3474 ^ ^ 

. ^ . 1. 0.0004X6000 
Loss m 6-m. nne = ^^ X2.2i'S^^ = 25.2 ft.; 



0.0004X6000 

0.583' 



Lossin 7-in. line= ^ ,q,i.25 — Xi.7^*^^^ = i2.7 ft.; 



0.0004X6000 
Loss m 8-m. line= ^ 55^1-25 — Xi.3^'^^' = 6.s ft. 

Friction horse-power : 

. . 1- 25.2X61.08X.45 . 

6-m. Ime, ^ = 1.26: 

550 

. ,. 12.7X61.08X.45 
7-m. hne, ^=0.61; 

'550 

„. ,. 6.5X61.08X0.45 

8-m. Ime, -^ =^=0.32. 

550 ^ 

Total horse-power to drive pump, assuming a 50 per cent 
overall efficiency, is as follows: 

6-in. line, 2.52; 
7-in. line, 1.22; 
8-in. line, 0.64. 



292 ELEMENTS OF HEATING AND VENTILATION ' 

Cost of power, using 200 heating days at an average of 15 hrs. 
at full capacity : 

6-in. line = 2.52X200X15 XiJ =$113.50; 
7-in. line = 1.22X45.00 = 54.90; 

8-in. Kne = . 64X45. 00 = 33.80. 

Radiation loss : 

6 ins., 0.03X1.734X6000 = 312 lbs. of steam; 

7 ins., 0.03X1.996X6000 = 359 lbs. of steam; 

8 ins., 0.03X2.255X6000 = 406 lbs. of steam. 

With heat worth 35 cts. per 1,000 lbs. of steam the cost of the 
radiation is 

312X200X15 ^ 

6 ms., ^^ -— ^Xo.35 =$327.60; 

1000 

359X200X15 ^^ , 

^^^^•' ^^ Xo.35= 376.50; 

406X200X15 

8 ms., Xo.ss= 426.00. 

1000 ^^ 

The cost of excavation and back filling for the pipe will cost 20 
to 30 cts. a cubic yard, but this item will not vary much, if at 
all, for the different sizes of pipes. 

The list prices per foot of the pipes and covering are as 
follows : 

For Pipe For Wood Casing 

6 ins., $1.88 $1.94 

7 ins., 2.35 2.16 

8 ins., 2.82 2.44 

Assume discount as 70-10-10 on pipe, 50-20 on casing. 

Cost of casing: 

6 ins. = $1 .94 X 6000 X .40 = $4660.00 ; 
7ins.= 2.i6x6oooX.40= 5180.00; 
8ins. = 2. 44 X 6000 X. 40= 5860.00; 



DISTRICT HEATING 293 

Cost of pipe: 

6ins.= 1.88X6000X0.243 =$2740.00; 
7ins.= 2.35X6000X0.243= 3420.00; 
8ins. = 2.82X6000X0.243= 4115.00. 

If interest amounts to 5 per cent, taxes to i| per cent, and 
depreciation to 4.6 per cent (if the life is taken at fifteen years), 
the yearly cost of the investment will be : 

6ins. = 740o.ooXii.i = $821.40; 

7 ins. =8600.00X11.1 = 954.60; 

8 ins. =9975.00X11.1 = 1107.22. 

The cost of installation will be taken to be the same for each 
line, as will practically be the case, or it might be considered 
to be included as a per cent of the cost of the pipe and casing 
and figured in as part of investment just computed. Yearly 
cost then becomes : 

For 6 ins. For 7 ins. For 8 ins. 

Interest $821.40 $954.60 $1107.22 

Radiation 327.50 376.50 426.00 

Power . 113-50 54-90 33-80 



Totalcost $1272.40 $1386.00 $1567.02 

This shows that the smalles. pipe is best. The yearly cost 
should now be worked out for a 5-in. pipe and the result would 
show a slight decrease in the cost ($1242.61). The use of a 
4-in. pipe would increase the cost of power so much that the 
total cost would be increased. The difference between the yearly 
cost of the 5 and 6 in. is so slight that it would be well to use the 
6 in., since if more water were needed this would care for it with 
less cost of power and the other items would be the same. For 
that reason it would be cheaper to operate than the 5 in. except 
under the conditions of the problem. 

For steam pipe there is not much power consumed, and if 
the pressure can be taken to a high point it may pay to use high- 
pressure steam, since this steam is more dense. The main 



294 ELEMENTS OF HEATING AND VENTILATION 

consideration in steam-pipe work is whether or not the small 
pipe with a higher temperature difference will radiate so much 
heat that its cost added to the yearly cost on the investment 
will be more or less than on a larger pipe with low-pressure steam, 
in which the cost of installation is greater, but the heat loss is 
less. If the computation is made it will be found that the 
yearly cost is less on the small pipe carrying high-pressure steam. 
If possible live steam should be used in the transmission main. 
When exhaust steam is to be used, large pipes have to be 
employed to accommodate the low-density steam. The method 
of calculation is similar to that used before. The items con- 
sidered are the cost per year for investment and loss of heat 
at different pressures, using the various sizes of pipes resulting 
from the use of the formula for size in terms of the drop, steam 
pressure and length (see p. 139). These systems are applied 
as shown in Figs. 206, 207, the first being for a town while the 
second is for an institution. Each of these is used in the same 
manner by assuming pressure drops and quantities from which 
the diameters are found, and then an economic study is made 
with a change in certain of the conditions, the idea being to 
make the operating cost and fixed charges as small as possible. 

The costs are usually figured per 1000 lbs. of steam, per 
1,000,000 B.t.u. or per square foot of radiation. The charges 
are about 60 cts. per 1000 lbs. of steam and 35 cts. per square 
foot of steam radiation per season and 20 cts. per square foot 
of hot-water radiation. 

Gifford states that the annual charge for heat should be 
divided monthly in the following proportion : 

October 3 per cent 

November 12 

December 18 

January 21 

February 19 

March 13 

April 8 

May 3 



DISTRICT HEATING 



295 




Fig. 206. — District Heating of a City. (From Catalogue of American District 

Heating Co.) 



296 



ELEMENTS OF HEATING AND VENTILATION 



The following might also be used in northern climates, where 
March is a hard month: 

October 5 per cent 

November 10 

December 15 

January 20 

February 20 

March 15 

April 10 

May 5 



100 per cent 




Fig. 207. — District Heating of an''lnstitution. 



The value of district systems is due to the fact that a uniform 
heat is always available and there is no dirt or expense for main- 
taining or caring for the furnace, ashes and coal. The expense 
may be higher than the cost of coal, but should not exceed the 
cost plus the cost of operating the furnace. The absence of 
dust from coal and ashes has undoubtedly a money value which,, 
although it is not possible to fix, nevertheless should be con- 
sidered in estimating the value of this method of heating. 

This system also gives a cleaner town in that the numerous 
smoking chimneys are taken away from the location of the 
high-grade property. 



DISTRICT HEATING 



297 



In maintaining mains care must be taken to stop all leaks 
at any place, for very small openings are great sources oi loss. 
A J-in. hole, for instance, at 5 lbs. steam pressure, would dis- 
charge about 36,000 lbs. of steam per month, using over two 
tons of coal. 

The pipe should be full- weight pipe (specially selected to see 
that all is uniform and of proper weight), and the fittings should 
be extra heavy. All breaks are guarded against, as it is very 
expensive to repair pipes installed in the usual manner. In 
designing tunnels it is well to place a number of inclined 
openings leading to the ground level at intervals for the intro- 
duction of new pipes when necessary. 



^^j^^^i;^;^^^^^^^^^^^^!^^^^^^^^^^^^ 



s 



V//////yyy/yyy^yy//^y'////y//yyy 




^ssss^g^s^^^^^^^^^^s^^ 



Fig. 208. — Oscillating Water Meter. 



When pipes and conduits are placed in streets the back fill 
must be well rammed and puddled to avoid subsequent settling, 
and on top of this fill a good concrete base should be put over 
the hole to support the pavement. 

The meters used for steam condensation should be of the 
oscillating bucket type. Fig. 208, so that no water will leak at 
times of small discharge. The trouble with many meters is the 
fact that they allow a small rate of flow to remain unrecorded 
and for that reason the type above is of value. To regulate the 
flow of water into buildings in the hot-water system it has 
been suggested to insert standard orifices in the service con- 



298 ELEMENTS OF HEATING AND VENTILATION 

nections. These are made smaller near the station, where the 
difference of pressure between main and return is greater than 
at the end. These smaller orifices prevent a large quantity 
from passing into the services near the station, which would 
mean a higher temperature on the return than should exist at 
this building. It would indicate that the water was not doing 
its proper work, as its return temperature was too high. By 
observing the return temperature from a building the correct- 
ness of the orifice may be known. If low, the orifice is too small; 
if high, the orifice is too large. 

There should be constant inspection of all manholes for the 
evidences of leakage from expansion joints, valves, conductors, 
and to see if traps are clean. These should be blown out and 
cleaned at regular intervals. 

One form of district heating is that used for car heating 
on railroad systems. The heat is supplied from the locomotive. 
A I -in. extra-heavy pipe is taken from the dome through a stop 
valve and a pressure regulator, the outlet of which is i^ and after 
passing the T for the gauge, the line enlarges to ij ins. It is 
connected to ij-in. covered pipes under the tender and cars 
by means of special steam hose couplers. Each coupler is pro- 
vided with a trap which opens to drain the line as soon as 
steam is cut from it. 

The pressure regulator is a spring-controlled reducing pres- 
sure valve of such a construction that it will operate properly 
on the moving locomotive. 

The ij-in. train pipe has a ij-in. branch under the center 
of each car and this is spKt into two i-in. branches, each one 
running to a i-in. angle valve under a seat near the center of 
each side. The Hne on each side enlarges to 2 ins. and a loop 
is taken along the side of the car, care being exercised to use a 
right-angle section at one end to care for expansion, as was done 
in the corner coil of Fig. 63. The condensation in this Hne 
is then carried through a trap and discharged from the system 
beneath the car. This trap is made on the same principle as 
was used in the thermograde motor valve, Fig. 79. As soon 
as steam strikes it the valve closes. There is usually a trap 



DISTRICT HEATING 299 

which opens as soon as the pressure is cut off, to ensure that all 
water is drawn off, thus preventing freezing. 

Each car is equipped with a train pipe valve at the center 
of the car or at the end. These valves are used to close off the 
train Hne at the last car. They are provided with traps to 
relieve the hne of water. 

The direct steam-heating system is valuable in that it is 
rapid, effective, and when cut out there is no danger of freezing. 
The objection is that there is no storage and as soon as steam 
is cut off the car begins to cool. For storage and for a less 
intense heat hot water is used. This is heated in a coil placed 
in a fire pot of a heater, or steam from a train line is introduced 
into a small pipe within the coil and heats the water. This 
avoids the cracking noises which occur with steam lines at times. 
By using brine the hquid is prevented from freezing. At times 
for storage terra cotta bricks are surrounded by a large pipe 
and these are heated by the steam. The tile retains the heat 
ior some time. 



CHAPTER XII 



TEMPERATURE CONTROL AND DRYING BY AIR 



The control of temperature is more or less important for the 
comfort of those occupying the rooms and for the economical 
operation of a plant. The great trouble with various systems 
for this purpose is the disarrangement of parts due to the 
delicacy of the apparatus and to the maltreatment which they 
receive from those who do not understand the adjustment of 
them. When they cease to operate properly the radiator valves 

cannot be opened or closed 
and hence the occupants of a 
room may be driven out by 
the cold or heat without 
power to correct the evil. 

There are several simple 
as well as some complicated 
systems applied to all methods 
of heating. 

The Johnson system of 
temperature control consists 
of a thermostat which con- 
trols the admission of air from 
a compressed-air supply into 
a case above a diaphragm at 
the top of the valve, Fig. 
209. This admission of air 
closes the valve. The air is 
compressed by electric motors or small water motors- 

At a given pressure of 14 or 15 lbs. in the storage tank the 
motors are shut off. The air is then carried to the thermostats 

300 




Fig. 209. — Section of Diaphragm Valve. 



TEMPERATURE CONTROL AND DRYING BY AIR 301 



in small pipes and from these it is conducted through other 

small pipes to the valves. The pipes are small in diameter and 

are usually concealed in the plaster. The air used is screened 

when entering the apparatus to pre- 
vent foreign particles entering the 

system. 

The thermostat is really a valve 

controUing the admission of air under 

pressure into the pipe leading to the 

radiator valve, or permitting the air 

to escape the valve line. The ther- 
mostat, Fig. 2io,is carried on the plate 

A, which is attached to the wall and 

the brass block B, which forms the 

end of the supply pipe C and the valve 

pipe or motor pipe D. The upper of 

the two pin valves EE is used to shut 

off the air if the thermostat is taken 

off, while the lower one regulates the 

flow to the valve motor. From the 

upper valve E the air is led by a 

crooked passage to the air valve F. 

This valve is closed in the figure and 

if there is any excess air in D it can 

escape around the spindle G. When 

the spindle is moved out the disc F 

opens the pipe C but closes the an- 
nular space around G so that the air 
cannot escape, and hence it passes 
into D. 

The rubber diaphragm K rests against a disc S, forming an 
air motor at /. By means of a side tube air is brought to the 
valve L from C. The valve L is adjustable, so that the amount 
of air admitted into the space / may be fixed. M is the outlet 
to this space, closed by the valve N. N is fastened to the lid, 
which is controlled by a bent piece of metal 0. This piece is 
fastened rigidly to the block R at one end, but the other end 




Fig. 2IO. — Mechanism of 
Johnson Thermostat. 



302 



ELEMENTS OF HEATING AND VENTILATION 



is free to move and operate the seat N. The strip is composed 
of strips of steel and brass and bends as its temperature changes, 
due to a difference in the co- 
efficients of expansion of the two 
metals. The strip will move to 
the right with a fall in tempera- 
ture and this will close the 
valve N, causing the pressure 
in / to increase until it is suffi- 
ciently great to move the piston 
S and the lever T, thus moving F 
and / to right and closing the 






Fig. 211. — Johnson Regulator. 

opening from C, the springs causing the motion of F to be rapid 
when it occurs. The steam valve now opens as air leaks from 



TEMPERATURE CONTROL AND DRYING BY AIR 303 

D and after the room becomes hot O moves to the left; air leaks 
from M and L, S moves to the right, moving H, G, and F to the 
left. This allows air to enter D and shuts off the valves on the 
radiator. The turning of the screw at U operates on the spring 



WMMMMMIMMMMMm 




X and so fixes the temperature at which will open the valve A^. 
This system as here described is apphed to any number of ther- 
mostats. A compressed-air main is connected to all of the ther- 
mostats and these connect the air to a group of radiators in a 
room. The same system may be applied to regulate dampers or 
coils in indirect heating, as will be described in the next system. 



304 



ELEMENTS OF HEATING AND VENTILATION 




TEMPERATURE CONTROL AND DRYING BY AIR 305 



The external appearance of the thermostat is shown in Fig 
211. The hole at the bottom is for the key adjustment for the 
temperature at which action takes place. 

The Powers system, as apphed to a plant using radiators 
for the heat loss and tempered air for ventilation so that the air 
for all rooms is at the same temperature, is given in detail 
in Fig. 212. It consists of motor-driven air compressor A and 
storage tank B connected by pipes to a series of thermostats 
C, and the thermostats are then connected by pipes to the 
motor valves G, G and G and the damper operator M. The ther- 





-^ 



Fig. 214. — Powers Thermostat. 

mostat allows air to enter the casing at the top of the valves 
G when the temperature is high and this air presses against a 
diaphragm attached to the valve stem, closing the valve, as 
described before. The thermostat on the side of the tempered 
air duct is heated by the metal of the case and operates the 
relays H, by which the valves on the various coils are thrown 
into action in succession, the action of the air when thrown on 
by the hot thermostat immediately opening the damper / by- 
passing the coil and then shutting down the sections. 

Fig. 213 illustrates a single-duct system of indirect heating. 
The fan B draws air through the tempering coil A , sending part 
of it through the main coil C and part beneath the coil into 
the tempered air chamber D. The thermostat E keeps the tem- 



306 



ELEMENTS OF HEATING AND VENTILATION 



perature at the right point by acting on the by-pass damper 
through the diaphragm motor and by acting on the coils A 
through the diaphragm valves. 




^ ) 



Fig. 215. — Powers Damper Regulator. 

The thermostats G in the rooms act on the diaphragm motors 
H and operate the mixing dampers, cutting off the hot air when 



TEMPERATURE CONTROL AND DRYING BY AIR 307 

more tempered air is needed. Each room will have a diaphragm 
motor acting on the mixing chambei dampers for its line. 

The motor part of the thermostat consists of a hollow cor- 
rugated vessel filled with a volatile fluid. The frame, Fig. 214, 
of the apparatus is covered with a casing to protect the motor 
parts. The pointer is attached to a screw which so moves the 
frame that a higher temperature is required for the volatile 
fluid to produce sufficient pressure to operate the two 
valves. 




Fig. 216. 
Honeywell Thermostat. 



Fig. 217. 
Honeywell Solenoid Regulator. 



Fig. 215 illustrates a method of using this corrugated vessel 
to produce the pressure to operate a diaphragm regulator. The 
metal casing, 12 ins. diameter, has a corrugated partition within 
it, the space on one side containing a volatile liquid. When 
this heats to a definite temperature some of the liquid volatilizes 
and compresses the air on the other side of the diaphragm and 
this acts on the water seal on top of the rubber diaphragm of 
the motor below and forces the lever down. In this way boiler 
draft or furnace draft may be regulated. The temperature 



308 



ELEMENTS OF HEATING AND VENTILATION 



around the vessel fixes the amount of volatiHzation and thus 
the position of the lever. For controlHng heaters or furnaces 
the Honeywell and the Minneapolis systems may also be used. 

The Honeywell temperature regulator consists of a ther- 
mostat, Fig. 216, in which the relative expansion of two dissimilar 




Fig. 218. — Honeywell Regulator. 



metals causes a strip to touch one of the contact points, the tem- 
perature at which the change from one to the other occurs 
depending on the position of the pointer at the bottom. This 
thermostat operates a solenoid, Figs. 217, 218, on the damper 
motor. If the temperature is high one point touches and the 
current causes the solenoid to lift the pawl, and a weight on a 
chain, Fig. 218, will cause the wheel to rotate, closing the draft 



TEMPERATURE CONTROL AND DRYING BY AIR 309 

and opening the check. The driving weight in this system has 
to be pulled up at intervals. This system is governed by one 
thermostat which is placed in the living room or one of the rooms 
which will have a fair average temperature. The system is 
simple and not expensive to maintain or control. 




Fig, 219. — Minneapolis Regulator. 



In the MinneapoKs heat regulator the thermostat, Fig. 221, 
releases a pawl on a clock which then revolves a driving 
wheel one-half revolution. The clock mechanism, Fig. 220, is 
such that the pawl is controlled by one point of the two contact 
points during one-half of the revolution while the other one con- 
trols the other. Thus, in Fig. 219, the position of the clock 
motor corresponds to the high temperature contact as the check 
damper is open and the draft is closed on a hot-air furnace. 



310 



ELEMENTS OF HEATING AND VENTILATION 



If the room gets chilled the thermostat, Fig. 221, touches on the 
other point and the cranks are moved through one-half of a rev- 
olution. These last two systems are apphed with one thermo- 
stat for the heater at some central point. 

In residences the doors are mostly open during the day, and 
hence for such this single thermostat is satisfactory. Such 
apparatus is of value for night heating where perishable objects 




Fig. 220.— Minneapolis Thermostat and Motor Works. 



are in rooms. Fig. 222 illustrates the application of the 
sylphon bellows ^ to a thermostatic control of temperature in 
a tank. The bellows A is connected by a tube B to the closed 
tube C, the whole system containing a volatile hydrocarbon. 
When the temperature is low in the tank the weight D opens 
the valve and permits the steam to enter the heating coils. 
Then as the temperature rises the vapor pressure from the liquid 
in C increases and pushes down on the valve, shutting off the 



TEMPERATURE CONTROL AND DRYING BY AIR 311 

steam supply. By moving the weight various temperatures 
may be obtained in C. 

Drying. The use of air for drying such things as bricks, 
lumber, woven goods or any other article, is one which warrants 
considerable attention. 



i^ 






Fig. 221. 
Minneapolis Thermostat. 



Fig. 222. 
Sylphon Thermostat Regulator. 



If air is heated its capacity for moisture mcreases because 
the weight of a cubic foot of moisture is greater at a higher 
temperature. Each cubic foot can be occupied by air and 
moisture, each constituent sustaining part of the atmospheric 
pressure. If, for instance, air saturated with moisture at 6o° 
F. is heated to 120° F., this air can hold more moisture because 
moisture at 120° F. occupies less space than that at 60° F., as 
it is under a greater pressure of saturation. Moisture at 60° 
is under 0.20 lb. pressure and weighs 5.8 grains per cubic foot, 



312 ELEMENTS OF HEATING AND VENTILATION 

while at 120° F. the pressure is 1.69 lbs. and the weight is 34.5 
grains per cubic foot. This means then that in time the air 
could absorb more than five times the original amount of mois- 
ture and carry it away from the article from which it absorbed 
the moisture. 

It must be remembered that this evaporation of water 
requires heat, and although the hot air can take it up this act 
will cool the air unless there is a certain amount of heat supplied 
from some source. This cooling action reduces the temperature 
of the air and with it its capacity for moisture. It is to be remem- 
bered that moisture will always enter any space until there is 
enough present in that space to saturate it at the given tem- 
perature. It is absolutely independent of the presence of the 
other substances in the space. Moisture when present will exert 
the pressure corresponding to its temperature. The cooling 
action is the feature of air conditioning used in summer weather. 
To illustrate these principles — suppose that bricks at a tem- 
perature of 80° weigh when wet 600 lbs. and that water is 20 
per cent of this weight. The problem is to find how much air 
is required to dry this if the air is heated to 190° by exhaust 
steam in a coil when taken from the atmosphere in which the 
dry- and the wet-bulb readings are 70° and 65° respectively. 

From Fig. 19, for air at 70° with a 5° drop for the wet bulb 
the relative humidity is 77 per cent and the moisture content 
is 6.4 grains per cubic foot. 

If now the air and its moisture are cooled to f F. when the 
necessary heat is given up to warm the clay and its water and 
to evaporate the water, the heat thus removed per cubic foot 
entering is 

Mcp{i()o — t)-\-mCps{'i-90 — t), .... (165) 

where M = mass of i cubic foot of entering air; 
Cp = specific heat of air; 

w = mass of moisture in i cu.ft. of entering air; 
Cps = specific heat of steam ; 
t = temperature of mixture. 



TEMPERATURE CONTROL AND DRYING BY AIR 313 
Now 

^= 6soR ^^^^) 

^6 = barometric pressure ; 

pm = pressure from moisture or vapor tension 

= steam pressure at 7o°Xrel. humidity (approxi- 
mately). 

w = 6.4 grains, 0.0009 lb. at 70°, or 0.0009 Xt — 

= 0.0007 at 190°. 
The heat removed from the brick per cubic foot of air is 

M' c{t- 60) +nM'{t- 60) -{-fiM'r (167) 

M' = weight of bricks per cubic foot of hot air; 
c — specific heat of material ; 
w = per cent of weight which is water; 
r = heat of vaporization. 

The moisture nM' should be sufficient to saturate the air at the 
temperature t. This air will not occupy the original volume, 
as the temperature is increased and the pressure is decreased. 
Both of these actions cause the volume of the air to increase. 
If the quantity of air is too great the discharged air will not be 
saturated, while if the quantity is driven through at a low rate 
it will become saturated and this will continue until all the 
moisture is removed. The following equations must therefore 
hold when the leaving air is saturated. 

Mcp{igo — t)-\-mCps(igo — t) =M^c(t — 60) 

-\-nM'(t-6o)-{'nM'r. . (168) 

{p,-Pm)U(>o-\-t) , . , 

nM' = j- — ■ w ^ — , — rm-m. . . . (169) 

{pb-pmt) [4^0 + JO) 

/>w = vapor tension for saturation at temperature t; 
nh = weight of moisture per cubic foot. 

In these two equations M' and / are unknown, and by trial 
the resulting values can be found. The best method is to assume 



314 ELEMENTS OF HEATING AND VENTILATION 

/ and solve for M' in each equation. When t is so assumed that 
the two values of M^ are the same the value will be the correct 



ones. 



M 144(14-7 -0-77X0.363) . „ 

M — 2 — ~7: =0.00 lb .; 

650X53-37 

c = o.2; 



assume 



/ = i5o; 
0.06X0.239X40+0.0007X0.5X40 

=ir'xo.2X9o+iir'x9o+K^/'x 1007.2; 

, .S86 
M'=- — = .00247 lb.; 
237 

1 ,^, (i4-7-Q-77Xo.363)(6io) 

-sM = 7 TT ^ 0.01032—0.0007; 

(i4.7-3-7i5)(53o) 

ikf'=o.o7. 

If now the temperature be made smaller, M' from the first equa- 
tions ^ill be larger and that from the second will be smaller. 
Suppose 100° is used; this gives as the two values of M': 

If' =0.0058; 
ikf' = o.oi23. 

A smaller value will give the correct amount. Suppose S^° is 
tried; the values are: 

M' =0.00705; 
ikf' = 0.0061. 

.¥'=0.00668; 
il/' = 0.00790. 



For 90° F.: 



By sketching the curves assumed to be straight lines between 
the last two values as shown in Fig. 223, the values of M and 
t Sit the points of intersection are found to be / = 87.0° and 
M'= 0.0069 respectively. This shows that the air at 190° F. 



TEMPERATURE CONTROL AND DRYING BY AIR 315 

is cooled to 87° F. by the drying action and that each cubic 
foot of air will dry 0.0069 ^b. of brick material and will leave 
at 87° F. The total quantity for air required will then be 



cubic feet air = 



600 
0.0069 



= 87,000 cu.ft. 



Of course if this remains here after the moisture is driven out 
the brick will warm up and probably leave at 190° F. This will 
change the problem somewhat, in that the amount of air will 



/M=.005 

















-^ 






^ ^ 






Mb.004 











tllo ^ 

Fig. 223. — Method of Finding Values of / and M'. 



have to be increased. The equation first used might have been 
put in the form: 

Mcp(igo — t) +mcpb{igo — t) = 

M'c (190-60)+ fiM' (/ - 60) + 7iM'r (170) 

Problems similar to this may be handled for drying any kind 
of substance. A similar method may be used to investigate 
the exhaust gases from a boiler or from kilns to find whether or 
not this gas will be sufficient to dry the material from the clay 
presses. The heat and moisture content of the gases in the hot 
and cold condition are considered in connection with the heat 
to be added and the moisture to be removed from the wet 
material. 



INDEX 



Absolute humidity, 20 
Air, 20 

allowance, 23 
, changes per hour, 23 
cooling, 43 
duct, 257 
, flow of, 187 
, free, 20 
Hne, 145 

per hour per person, 23 
, properties of, 38 

space, 58 
, tempered, 12, 13 

valve, loi, 145 
, vitiated, 21 
Allen, III 

automatic air valve, loi 
American District System, 285 
Radiator Co., 74, iii 
Anchors, 136 
Anemometer, 204 
Angle valve, 92 
Arch, 51 

Area flues, 176, 207, 208, 231 
Area pipes, 86, 138, 141, 163, 207, 208 
Argon, 20 
Asbestos, 146 
Auto valves, 96, 98 

B 

Barrus, 146 
Base ring, 256 
Bends, 281 
Billings, 26 
Blast area, 220 
Boiler, 2 

, locomotive, 268 

, sectional, 262 
sizes, 271-2 
size determinations, 274-5 



Boltzman, 106 
Bonnet, 242, 243, 259 
Book tile, 62 
Boots, I, 244 
Bottomley, 105 
Bottom support, 75 
Boxes, 178 

for registers, 243-6 
Box radiators, 76 
Branch, 3, 155 
Bricks, 58 

, Haverstraw, 58 

, hollow, 58 
British thermal unit, 45 
Buffalo Forge Co., 117 

coils, 86, 1 1 5-1 1 7 
, size, 185 
, loss in, 215 
By-pass plate, 256 



C, values of, 49 

Calculations, boiler size, 289 
coefficient K, 53 
, direct heating, 148 
, district system, 289 
, fans, 223 
, flue size, 210 
, furnace heating, 249, 274 
, furnace size, 273 
, heat, 118 

, hot-water system, i6q 
, indirect heating, 171 
, mill heating, 227 
, natural draft, 178 
, pipe size, 139 
, plenum system, 183-228 

Calorie, 45 

Carbon dioxide, 20 

apparatus, 24 
bottle, 25 

317 



318 



INDEX 



Carbon dioxide, exhaled per person, 22 
, permissible amount 21 

Car heating, 298 

Carpenter, R. C, 69, iii, 139 

Carpenter's rule, 69, 253 

Carrier, W. H., 32 

Carrier's air washer, 39 

Casing, i, 257 

Ceiling, flush, 60 
plates, 135 
values of K, 65 

Cellar plan for direct heating, 150 
for hot-air furnace, 250 
for hot water, 170 
for indirect heating, 177 

Changes of air per hour, 23 

Chases, 144 

Chezy's formula, 142 

Chimneys, 274, 276 

Circulation, sluggish, 129 

City, district heating of, 295 

Clapboards, 58 

Coefficient of transmission, 48 
, C, 49 

, e, 51 
K, 64-65 
Coils, 86, 88 

, corner, 85 
, main, 174 
, miter, 92 
, resistance, 9 
, size, 185 
, tempering, 174 
Cold-air duct, 252 
pit, 256 

supply, 238, 253 
Collars, 245 

Combustion chamber, 255 
Complete circuit system, 129, 157 
Concealed work, 145 
Concrete, value of K, 64 \ 
Conduction, 46 

constant, 47 
Conduits, 282-4 

, loss from, 288 
Connections, 2, 132 

, branches, 155, 137 
, radiators, 132, 145 
Constant of conduction, 47 

of transformation, 45 
Convection, 46 
Cooling air, 43 
Cork, 146 



Corner coils, 85 

valves, 96 
Corrugated pipes, 281 
Cost of installing, 293 
of operation, 293 
Covering, 287 

, block, 148 
, pipe, 146 
, plaster, 148 
, saving from, 148 
, sectional, 148 
, value of, 147 
Cox, Abram, Stove Co., 261 
Cubic feet per sq.ft. radiation, 131, 159 
Curves, cooling air, 43 

, equivalent pipes, 200 

, friction factors, 196 

, heating value of coils, 11 2-1 16 

, method of solving equations, 

315 
, moisture in air, 29-32, 37 
, pressure in fans, 219 
, relative humidity, 29-32, 37 
J temperature from coils, 1 2-1 16 
, values of heat loss from con- 
duits, 289 
Cut-off plate, 256 

D 

Dalby, 106 
Damper, 13, 178, 234 

, when omitted, 245 
Design, district mains, 288 
, direct heating, 148 
, hot-water heating, 169 
, indirect heating, 171, 227, 183— 
228 
Determination of K, no 

, fan size, 223 
, pipe size, 139 
Development of building, 1 34-1 51 
Dew point, 26 

apparatus, 26 
Direct heating, 127 
Direct-indirect heating, 8 

radiator, 76, 7 
Direct radiation, i, 4, 127 
Distributing main, 2, 129 
Distributors, O. S., 158 
District heating, 279 

, value of, 296 
Dome, I 

Double ducts, 13 
Down takes, 75 



INDEX 



319 



Drip pots, 143 

Drop, pressure, 193 

Drying, 309 

Ducts, 12, 178 

, single system, 14, 173, 214 

, double system, 13, 174, 210, 213 

Duiong, 105 

Dynamic pressure, 191 



Eccentric fittings, 154 
Effect of exposure, 68 

of intermittent heat, 68 
Elbows, 247 

, resistance, 140 
Electric heating, 8 
meter, 206 
radiators, 9 
Eliminator, 40 

, glass surface, 253 
Equivalent, lengths, 197 
, pipes, 197 
, temperatures, 71 
, volume, 253 
Evans, 290 

Evaporation requires heat, 310 
Excelsior indirect radiator, 90 
Expansion apparatus, 281 
joints, 138, 281 
of pipes, 138 
tank, 165 
Exposure factor, 68 



Factory heating, 233 
Fan blowers, 6, 8 
Fans, 6, 8, 216 

, dimensions, 221 

, power for, 221 

, power capacity and speed, 223 

, pressure from, 217 

, tables for, 225, 226 
with furnace, 249 
Ferrel, 28 
Filters, 41 
Fire pot, i, 255 
Fire proof floor, 69 
Flat arcb, 61 
Floors, 59 
Floor box, 243 
plate, 135 

, slow burning, 60 

, reinforced concrete, 60 



Floor tile arch, 61 
, values of K, 65 
and ceihng vent, 10 
Flow of air, 187 

of steam, 141 
of water, 290 
) main, 2, 153-4 
Flue area, 175, 20*, 208, 210, 231 
radiator, 76 
smoke, 274-6 
velocities, 210 
Flues, 240 

Forced circulation, 171 
Free air, 20 
French windows, 123 
Friction coefficient, 195 
factor, 195-6 
loss, 192 
loss, table, 208 
Fuller, Warren & Co., 
Furnace, hot-air, i, 255 
heating, i, 237 
position, 250 
, size, determination, 273 
, size of, 253, 269, 270 
, with fan, 249 
Furred, 58 
Fufring strips, 58 



Gauge metal, 179 
Generator, Honeywell, 166 
Gib panel > 80, 252 
Gifl'ord, 294 

Glass area, equivalent, 253 
Glower, luminous radiator, 9 
Goverment tile, 62 
Graff Co., 255-7 
Grashof, 49, 51 

H 

Hair felt, 146 
Hammering, 128 
Hangers, 136 
Haven, 290 
Head, loss of, 190 

, total, 197 
Heater, 2 

, loss of pressure in, 214 

, main. 174 

, positivflo, 88 

, sectional, 262 

, tempering, 174 

, Vento, 89 



320 



INDEX 



Heat for ventilation air, 69 
from lights, 70 
from motors, 70 
from persons, 70 
Heating, direct steam, 127 
, district, 279 
, furnace, 237 
, hot water, 153 
, indirect, 171 

, surface per cubic foot, 131, 159 
, surface required for natural 
draft stacks, 176 
systems, merits of, 276 
Heat loss, 45 

with covered pipes, 147 
through walls, 47, 69 
stacks, I 
transmission through radiators, 

105 
Helium, 20 
Hoffman, 242 
Honeywell Co., 163 

generator, 166 
temperature regulator, 

306 
valves, 164 
Horse-power for blowing, 208 
Hot-air furnace, i, 255-262 

heating, 237 
Hot- water heating, 153 
radiators, 75 
House plans, 122 
Housing, 217, 218 
Humidifiers, 39 
Humidity, 26 

, absolute, 20 
, relative, 20 
Humphrey gas heater, 267 
Hydraulic radius, 142 
Hydrodeik, 30 
Hygrometer, 26 



Ideal Junior heater, 265 

Indirect heaters, transmission, 1 1 1 

heating, 171 

, calculations, 171, 183, 
228, 178 

radiators, 90-92 

systems, 5 
Inside circulation, 239 
Intermittent heat factor, 68 
Isometric drawing, 132 



Jenkins Bros, valves, 94 
Johnson's system, 300 



Kelsey Co., 259 
Kinealy, 67 
Krypton, 20 



Lambrecht polymeter, 31 

Lath, 58 

Law, Stefan Boltzman, 106 

, Stewart Kirchhoff, 106 
Leader, i, 240, 243 
Leakage, 11 

air, 46 
Leg, detachable, 81 
loops, 81 
section, 75 
, vertical, 130 
Libra automatic air valve, 10-2 
List price, 86 

Lock and shield radiator valve, 96 
Loops, 74 

Loss from conduits, 288 
ducts, 232 
water pipes, 290 
of head, 190, 192 
of heat, 45 
of pressure, 214 
Luminous radiator, 9 
Lunge, 26 

M 

Magnesia, 146 
Main, 127, 128 
Manholes, 284 
Masonry, values of K, 64 
Massachusetts fan coils, 86 

fans, 216 
Measurements, radiators, 83 

, Vento heaters, 90 
Metal gauge, 179 
Metargon, 20 
Meter, electric, 206 

, oscillating, 297 

, Venturi, 204 
Mill heating, 233 

or slow-burning construction, 60 
Mills system, 129 
Mineral wool, 146 i 
Minneapolis temperature regulator, 307 



INDEX 



321 



Miter coil, 92 

Modulation valve, 96, 98 

Moisture, 26 

Monash value, 100 

Monthly percentage of heat, 294 

Motor discharge valve, 99 

N 
Natural draft circulation, 171 
Neon, 20 
Newton, 105 
Nicholson, 106 
Nipples, hexagon, 89 

, push, 264 
Nitrogen, 20 
Norwall automatic air valve, 103 

packless valve, 92 
Numbers, designating, 119 

O 
Offset fittings, 154 
Offsets, 247 
Orifice, standard, 202 
O. S. connector or distributors, 158 
Outlets, 163, 168 
, size, 132 
Overhead system, 129 
Oxygen, 20 
Ozonator, 14 
Ozone, 14-19 



Packless valves, 92 
Partial pressure, 28 
Partitions, 63 

, values of K, 65 
Paschen, 105 
Paul system, 145 
Perfection pin radiator, 92 
Peripheral speed, 217-220 
Personal amount of air, 23 

exhalation of CO2, 22 
Petavel, 105 
Petit, 105 
Pettenkofer, 21 

Pettersson's CO2 apparatus, 24 
Phenolphthalein, 26 
Pierce Co., 264 
Piezometers, 190 
Pipe coils, 84 

coil radiators, 82 

, concealed, 144 

covering, 146 



Pipe, double system, 128 
, exposed, 144 
, full weight, 297 
, list price, 86 
, single system, 127 
, size of hot- water, 159 
, sizes, 86 
, wrought iron, 86 
Pitch of hot-air pipes, 244 
of steam pipes, 143 
Pitot pressure, 191 

tubes, 191 
Plate warmers, 81 
Plenum, 8, 171 
Pockets, 128, 144 
Polymeter, 31 
Positivflo heater, 88 
Power for fans, 221 
Powers system, 302 
Pressed steel radiator, 82 
Pressure in fans, 217 

, dynamic, 191, 217 
, loss of, 191-3 
, measures of, 188 
, partial, 28 
, Pitot, 191 
, saturation, 29 
, static, 191, 217 
, velocity, 191, 217 
Properties of dry and saturated air, 2>^ 
Psychrometer, 27 

R 

Radiation, 46 

from conduits, 288 
Radiator, i, 73, 255 
, circular, So 

connections, 132, 145 
, comer, 80 

designation, 135 

dimensions, 83 
, dining room, 81 
, electric, 9 

foot ups, 82 
, furnace, 255 
, heat transmission, 105, 159. 

heights, 80, 83 
, hot- water, 153 
, low, 80 

outlets, 132, 163, 168 
, pantry, 81 

pedestal, 82 
, pipe coils, 82 
, pressed steel, 82 



322 



INDEX 



Radiator selection, 80, 132 
, size required, 131 
table, 149 

tapping, 132, 163-8 
, test of, no 
, values of A', no 
, wall, 81 
, window, 80 
Radifier, 100 
Rate of transmission, 47 
Recirculating duct, 237 
Reducers, 144 
Register, i 

Register box, 243, 246 
faces, 179, 209 
location, 329 
, special, 247 
Reheater, 12 

Reinforced cinder concrete floor, 60 
Relative humidity, 20, 26 
Resistance, valves and elbows, 140 
Return, 3 

for different buildings, 130 
, size of, 142 
Reitschel, H., 47, 49 
Right and left nipples, 73 
Risers, i, 2, 127, 128 

, arrangement of, 134 
control, 135 
designation, 135 
table, 149 
Rococo wall radiator, 81 
Rosetti, 105 
Rudd gas heater, 268 



Sand ring, 259 
Saturation, 20 

pressure, 29 
School building, 180 

heating, 248 
Screens, 252 
Sealed return, 130 
Sections of boiler, 264 
Sheathing boards, 58 
Shingles, 58 
Shoes, I, 244 
Sickels, 139 
Single-duct system, 14 
-flow system, 153I 
-pipe system, 127 
Size of flues, 179 

furnace, 253 

mains, 138, 141, 163 



Size of pipes, hot-water, 159 

supply and return, 187 

Vento heater, 186 
Skew backs, 61 
Sleepers, 60 
Sleeves, 136 
Sling psychrometer, 27 
Slow-burning construction, 60 
Smoke flue, 274-276 

outlet, 256 
Sodium carbonate, 26 
Spangler, 119 
Spence boiler, 265 
Stacks, I, 5, 8, 240 
Stateroom type electric radiator, 9 
Static pressure, 191 
Steam flow, 141 

pipes, pitch of, 143 
Stefan, 105 

Stefan-Boltzman Law, 106 
Sterling Radiator, 92 
Stove cement, 259 
Studs, 58 
Sturtevant, B. F. & Co., 86 

coils, 86 
Supports, 282-4 
Swinging ells, 137, 281 
Sylphon, 94 

air and vacuum valves, 104 
air valve, 103 
packless radiator valve, 94 
vent valves, 104 



Tables, air per person, 

, properties, 38 
, velocity, 209 
, boilers, 271-2 

, Buffalo Forge Co. heater, 185 
, capacity pipes, 138 
, coefficients, 64, 65 
, conversion factors, 45-6 
, covering loss, 147 
, cubic feet per square foot heat- 
ing surface, 131, 159 
, equivalent pipes, 208 

temperature, 72 
, expansion of pipes, 138 

tanks, 165 
, exposure allowance, 68 
, fans, 225-6 
, friction factor, 196-7 
, loss, 208 



INDEX 



323 



Tables, furnace heating, 238, 251 
, size, 269-70 

, gauge thickness, 179 
, heat changes, 294-6 
, heaters, 186, 187 
heat given out, 70 

transmission coefficient, 64, 

6S 
, house heating, 120-1 
, indirect heating, 178 
, loss pressure in heaters, 215 
, pipe sizes, air, 207 

, steam, 86, 138, 141 
, water, 163 
, pressure, 207 
, properties of air, 38 
, radiator list, 149, 170 
, radiators, 81, 83 
, riser list, 149, 170 
, room temperature, 66-7 
, school building, 181 
, size, iron, 179 

, pipes, 86, 138, 141, 163, 207 
, risers, 135 
, tin, 247 
, tappings, 132, 163, 168 
, temperature effect, 209 

rooms, 66-7 
, tin sizes, 247 
, Vento heater, 186 
, velocity, 20, 209 
, water weight, 143, 161 
Tank, expansion, 165 
Tappings, radiator, 163-8 
Temperature allowance for height, 68 
atmosphere, 66 
control, 300 
, effect of, 198 
, entrance, 172 
, equivalent, 71 
, inlet, 237 
, maximum, on hot water, 

166 
outlet from heater, 112 
rooms, 66 
Tempered air, 12, 13 
Test of radiator, no 
Theatre heating, 235 
Thermal units, 45 
Thermmograde system, 96 
Thermostat, 300, 303, 308, 312 
Thermostatic motor, 13 
Thickness of flues, 179 
Thomas, 206 



Tin, size of, 247 

Tongued and grooved l)oards, 58 

Top guide, 75 

Total head, 197 

Transformation fact rs, 45 

Transmission, rate of, 47 

coefficient, 48 

of heat through radiators, 
105 _ 
Traps, use of for buildings on same le- 

turn, 130 
Tunnel, 282 
Tw^o ducts, 13 
Two-pipe system, 128 



Vacuum system of heating, 129 

of ventilation, 8, 171 
valves, 103-4 
Valves, 92 

, air, loi, 102 
, corner, 96 
, lock and shield, 96 
, Monash, 108 
, motor discharge, 99 
, positions of, 144 
, 0- O. water, 95 
, resistances, 140 
, sylphon packless, 94 
Vapor tension, ^(^ 
Variators, 281 
Velocities, 209, 210 
Velocity, effect on transmission, 107 
for natural draft, 175 
in ducts, 183 
in hot water-pipes, 159 
pressure, 191 
Vent flue, 173 

stack, I, 242 
Vent values, 104 
Ventilation for schools, 181 
, heat for, 69 
, method of, 1 1 
Vents, 92 
Vento heater, 89, 90 

, measurements, 90 
, size, 186 
Venturi meter, 204 
Vitiated air, 21 
Volume equivalent, 253 
Voussoirs, 61 



324 



INDEX 



W 

Wall, 58 

section, 52, 57 
, type electric heater, 9 
, values of K, 64 
, wooden, 59 
Warren, Webster & Co., 40, 43 

washer, 40 
valves, 98-9 
Washers, 39 
Water hne, 127 
pan, 261 
vapor, 20 



Water, weight of, 143, 161 

Weber, 105 

Wet- and dry-bulb hygrometer, 27 

Williams, 290 

Window constants, 64-5 

, French, 123 
Wood floor, 54 
walls, 59 

, value of K, 65 



Xenon, 20 



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Stockbridge's Rocks and Soils 8vo, 

' Stone's Practical Testing of Gas and Gas Meters 8vo, 

* Tillman's Descriptive General Chemistry 8vo, 

* Elementary Lessons in Heat 8vo, 

Treadwell's Qualitative. Analysis. (Hall,) 8vo. 

Quantitative Analysis, (Hall.).. .8vo, 

Turneaure and Russell's Public Water-supples 8vo, 

Van Deventer's Physical Chemistry for Beginners. (Boltwood.) 12mo, 

Venable's Methods and Devices for Bacterial Treatment of Sewage 8vo, 

Ward and Whipple's Freshwater Biology. (In Press.) 

Ware's Beet-sugar Manufacture and Refining. Vol. 1 8vo, 

Vol. II 8vo, 

Washington's Manual of the Chemical Analysis of Rocks 8vo, 

* Weaver's Military Explosives 8vo, 

Wells's Laboratory Guide in Qualitative Chemical Analysis 8vo, 

Short Course in Inorganic Qualitative Chemical Analysis for Engineering 
Students 12mo, 

Text-book of Chemical Arithmetic , 12mo, 

Whipple's Microscopy of Drinking-water 8vo, 

Wilson's Chlorination Process 12mo, 

Cyanide Processes 12mo, 

Winton's Microscopy of Vegetable Foods 8vo, 

Zsigmondy's Colloids and the Ultramicroscope. (Alexander.). .Large 12mo, 



CIVIL ENGINEERING. 

BRIDGES AND ROOFS. HYDRAULICS. MATERIALS OF ENGINEER- 
ING. RAILWAY ENGINEERING. 

* American Civil Engineers' Pocket Book. (Mansfield Merriman, Editor- 

in-chief.) 16mo, mor. 5 00 

Baker's Engineers' Surveying Instruments 12mo, 3 00 

Bixby's Graphical Computing Table Paper 19i X 24i inches. 25 

Breed and Hosmer's Principles and Practice of Surveying. Vol. I. Elemen- 
tary Surveying 8vo, 3 00 

Vol. II. Higher Surveying 8vo, 2 50 

* Burr's Ancient and Modern Engineering and the Isthmian Canal 8vo, 3 50 

Comstock's Field Astronomy for Engineers 8vo, 2 50 

* Corthell's Allowable Pressure on Deep Foundations 12mo, 1 25 

Crandall's Text-book on Geodesy and Least Squares 8vo, 3 00 

Davis's Elevation and Stadia Tables 8vo, 1 00 

* Eckel's Building Stones and Clays 8vo, 3 00 

Elliott's Engineering for Land Drainage 12mo, 2 00 

* Fiebeger's Treatise on Civil Engineering 8vo, 5 00 

Flemer's Photo topographic Methods and Instruments 8vo, 5 00 

Folwell's Sewerage. (Designing and Maintenance.) 8vo, 3 00 

Freitag's Architectural Engineering 8vo, 3 50 

French and Ives's Stereotomy 8vo, 2 50 

* Hauch and Rice's Tables of Quantities for Preliminary Estimates. . . 12mo, 1 25 

Hayford's Text-book of Geodetic Astronomy 8vo, 3 00 

Hering's Ready Reference Tables (Conversion Factors.) 16mo, mor. 2 50 

Hosmer's Azimuth 16mo, mor. 1 00 

* Text-book on Practical Astronomy 8vo, 2 00 

Howe's Retaining Walls for Earth 12mo, 1 25 

* Ives's Adjustments of the Engineer's Transit and Level 16mo, bds. 0*25 

Ives and Hilts's Problems in Surveying, Railroad Surveying and Geod- 
esy 16mo, mor. 1 50 

* Johnson (J.B.) and Smith's Theory and Practice of Surveying . Large 12mo. 3 50 
Johnson's (L. J.) Statics by Algebraic and Graphic Methods 8vo, 2 00 

* Kinnicutt, Winslow and Pratt's Sewage Disposal 8vo, 3 00 

* Mahan's Descriptive Geometry 8vo. 1 50 

Merriman's Elements of Precise Surveying and Geodesy 8vo, 2 50 

Merriman and Brooks's Handbook for Surveyors 16mo, mor. 2 00 

Nugent's Plane Surveying 8vo, 3 50 

•Qgden's Sewer Construction 8vo, 3 00 

Sewer Design , 12mo. 2 00 

6 



* Ogden and Cleveland's Practical Methods of Sewage Disposal for Resi- 

dences, Hotels, and Institutions. 8vo, 

Parsons's Disposal of Municipal Refuse 8vo, 

Patton's Treatise on Civil Engineering. 8vo, half leather, 

Reed's Topographical Drawing and Sketching 4to, 

Riemer's Shaft-sinking under Difficult Conditions. (Corning and Peele.).8vo. 

Siebert and Biggin's Modem Stone-cutting and Masonry , 8vo, 

Smith's Manual of Topographical Drawing. (McMillan.) 8vo, 

Soper's Air and Ventilation of Subways 12mo, 

* "Tracy's Exercises in Surveying 12mo, mor. 

Tracy's Plane Surveying 16mo, mor. 

Venable's Garbage Crematories in America 8'''o, 

Methods and Devices for Bacterial Treatment of Sewage 8vo, 

Wait's Engineering and Architectural Jurisprudence 8vo, 

Sheep, 

Law of Contracts 8vo, 

Law of Operations Preliminary to Construction in Engineering and 

Architecture 8vo, 

Sheep, 
Warren's Stereotomy — Problems in Stone-cutting. 8vo, 

* Waterbury's Vest-Pocket Hand-book of Mathematics for Engineers. 

21 X 5f inches, mor. 

* Enlarged Edition. Including Tables n:or. 

Webb's Problems in the Use and Adjustment of Engineering Instruments. 

16mo, mor. 
Wilson's Topographic, Trigonometric and Geodetic Surveying 8vo, 

BRIDGES AND ROOFS. 

Boiler's Practical Treatise on the Construction of Iron Highway Bridges.. 8vo, 

* Thames River Bridge Oblong paper, 

Burr and Falk's Design and Construction of Metallic Bridges 8vo, 

Influence Lines for Bridge and Roof Computations 8vo, 

Du Bois's Mechanics of Engineering. Vol. II Small 4to, 

Foster's Treatise on Wooden Trestle Bridges 4to, 

Fowler's Ordinary Foundations 8vo, 

Greene's Arches in Wood, Iron, and Stone 8vo, 

Bridge Trusses £vo, 

Roof Trusses 8vo, 

Grimm's Secondary Stresses in Bridge Trusses ;8vo, 

Heller's Stresses in Structures and the Accompanying Deformations.. . .8vo, 

Howe's Design of Simple Roof- trusses in Wood and Steel 8vo, 

Symmetrical Masonry Arches 8vo, 

Treatise on Arches 8vo, 

* Hudson's Deflections and Statically Indeterminate Stresses Small 4to, 

* Plate Girder Design 8vo, 

* Jacoby's Structural Details, or Elements of Design in Heavy Framing, 8vo, 
Johnson, Bryan and Tumeaure's Theory and Practice in the Designing of 

Modern Framed Structures Small 4to, 

* Johnson, Bryan and Tumeaure's Theory and Practice in the Designing of 

Modem Framed Structures. New Edition. Part 1 8vo, 

* Part II. New Edition 8vo, 

Merriman and Jacoby's Text-book on Roofs and Bridges: 

Part I. Stresses in Simple Trusses 8vo, 

Part II. Graphic Statics 8vo, 

Part III. Bridge Design 8vo, 

Part IV. Higher Structures 8vo, 

Ricker's Design and Construction of Roofs. (In Press.) 

Sondericker's Graphic Statics, with Applications to Trusses, Beams, and 

Arches 8vo, 

Waddell's De Pontibus, Pocket-book for Bridge Engineers 16mo, mor. 

* Specifications for Steel Bridges 12mo, 

HYDRAULICS. 

Barnes's Ice Formation 8vo, 3 00 

Bazin's Experiments upon the Contraction of the Liquid Vein Issuing from 

an Orifice. (Trautwine.) 8vo, 2 00 

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Bovey's Treatise on Hydraulics 8vo, $5 00 

Church's Diagrams of Mean Velocity of Water in Open Channels. 

Oblong 4to, paper, 1 50 

Hydraulic Motors 8vo, 2 00 

Mechanics of Fluids (Being Part IV of Mechanics of Engineering) . , 8vo, 3 00 

Coffin's Graphical Solution of Hydraulic Problems. , . 16mo, mor. 2 50 

Flather's Dynamometers, and the Measurement of Power 12mo, 3 00 

Fohvell's Water-supply Engineering 8vo, 4 00 

Frizell's Water-power 8vo, 5 00 

Fuertes's Water and Public Health 12mo, 1 50 

Water-filtration Works 12mo, 2 50 

Ganguillet and Kutter's General Formula for the Uniform Flow of Water in 

Rivers and Other Channels. (Hering and Trautwine.) 8vo, 4 00 

Hazen's Clean Water and How to Get It Large 12mo, 1 50 

Filtration of Public Water-supplies 8vo. 3 00 

Hazelhurst's Towers and Tanks for Water-works 8vo 2 50 

Herschel's 115 Experiments on the Carrying Capacity of Large, Riveted. Metal 

Conduits 8vo, 2 00 

Hoyt and Grover's River Discharge 8vo. 2 00 

Hubbard and Kiersted's Water-works Management and ^Maintenance. 

Svo, 4 00 

* Lyndon's Development and Electrical Distribution of Water Power. 

Svo, 3 00 
Mason's Water-supply. (Considered Principally from a Sanitary Stand- 
point.) Svo, 

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* Molitor's Hydraulics of Rivers, Weirs and Sluices Svo, 

* Morrison and Brodie's High Masonry Dam Design Svo, 

* Richards's Laboratory Notes on Industrial Water Analysis Svo, 

Schuyler's Reservoirs for Irrigation, Water-power, and Domestic Water- 
supply. Second Edition, Revised and Enlarged Large Svo, 

* Thomas and Watt's Improvement of Rivers 4to, 

Turneaure and Russell's Public Water-supplies Svo, 

* Wegmann's Design and Construction of Dams. 6th Ed., enlarged 4to, 

Water-Supply of the City of New York from 1658 to 1895 4to, 

Whipple's Value of Pure Water Large 12mo, 

Williams and Hazen's Hydraulic Tables Svo, 

Wilson's Irrigation Engineering Svo, 

Wood's Turbines Svo, 



MATERIALS OF ENGINEERING. 

Baker's Roads and Pavements Svo, 5 00 

Treatise on Masonry Construction Svo, 5 00 

Black's United States Public Works Oblong 4to, 5 00 

* Blanchard and Drowne's Highway Engineering, as Presented at the 

Second International Road Congress, Brussels, 1910 Svo, 2 00 

Bleininger's Manufacture of Hydraulic Cement. (In Preparation.) 

* Bottler's German and American Varnish Making. (Sabin.) . .Large 12mo, 3 50 

Burr's Elasticity and Resistance of the Materials of Engineering Svo, 7 50 

Byrne's Highway Construction Svo, 5 00 

Inspection of the Materials and Workmanship Employed in Construction. 

16mo, 3 00 

Church's Mechanics of Engineering Svo, 6 00 

Mechanics of Solids (Being Parts I, II, III of Mechanics of Engineer- . 

ing Svo, 4 50 

Du Bois's Mechanics of Engineering. 

Vol. I. Kinematics, Statics. Kinetics Small 4to, 7 50 

Vol. II. The Stresses in Framed Structures, Strength of Materials and 

Theory of Flexures Small 4to, 10 00 

* Eckel's Building Stones and Clays Svo, 3 00 

* Cements, Limes, and Plasters Svo, 6 00 

Fowler's Ordinary Foundations '. Svo, 3 50 

* Greene's Structural Mechanics Svo, 2 50 

HoUey's Analysis of Paint and Varnish Products. (In Press.) 

* Lead and Zinc Pigments Large 12mo, 3 OO 

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* Hubbard's Dust Preventives and Road Binders Svo, S3 00 

Johnson's (C. M.) Rapid Methods for the Chemical Analysis of Special Steels. 

Steel-making Alloys and Graphite Large 12mo, 

Johnson's (J. B.) Materials of Construction Large Svo, 

Keep's Cast Iron 8vo, 

Lanza's Applied Mechanics 8vo. 

Lowe's Paints for Steel Structures 12mo, 

Maire's Modem Pigments and their Vehicles 12mo, 

* Martin's Text Book on Mechanics. Vol. I. Statics 12mo, 

* Vol. II. Kinematics and Kinetics 12mo, 

* Vol. III. Mechanics of Materials 12mo, 

Maurer's Technical Mechanics Svo, 

MerriU's Stones for Building and Decoration Svo. 

Merriman's Mechanics of Materials Svo, 

* Strength of Materials 12mo, 

Metcalf 's Steel. A Manual for Steel-users .\2mo, 

Morrison's Highway Engineering , . ^ = , . = . . Svo, 

* Murdock's Strength of Materials 12mo, 

Patton's Practical Treatise on Foundations Svo, 

Rice's Concrete Block Manufacture Svo, 

Richardson's Modem Asphalt Pavement Svo, 

Richey's Building Foreman's Pocket Book and Ready Reference. 16mo, mor. 

* Cement Workers' and Plasterers' Edition (Building Mechanics' Ready 

Reference Series) 16mo, mor. 

Handbook for Superintendents of Construction 16mo, mor. 

* Stone and Brick Masons' Edition (Building Mechanics' Ready 

Reference Series) 16mo, mor. 

* Ries's Clays : Their Occurrence, Properties, and Uses Svo, 

* Ries and Leighton's History of the Clay-working Industry of the United 

States Svo, 

Sabin's Industrial and Artistic Technology of Paint and Varnish Svo, 

* Smith's Strength of Material 12mo, 

Snow's Principal Species of Wood Svo, 

Spalding's Hydraulic Cement 12mo, 

Text-book on Roads and Pavements 12mo, 

* Taylor and Thompson's Concrete Costs » Small Svo, 

* Extra'cts on Reinforced Concrete Design Svo, 

Treatise on Concrete, Plain and Reinforced Svo, 

Thurston's Materials of Engineering. In Three Parts Svo, 

Part I. Non-metallic Materials of Engineering and Metallurgy. . . .Svo, 

Part II. Iron and Steel Svo, 

Part III. A Treatise on Brasses, Bronzes, and Other Alloys and their 

Constituents Svo, 

Tillson's Street Pavements and Paving Materials Svo, 

Turneaure and Maurer's Principles of Reinforced Concrete Construction. 

Second Edition, Revised and Enlarged Svo, 

Waterbury's Cement Laboratory Manual 12mo, 

* Laboratory Manual for Testing Materials of Construction 12mo, 

Wood's (De V.) Treatise on the Resistance of Materials, and an Appendix on 

the Preservation of Timber Svo, 2 00 

Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and 

Steel Svo, 4 00 

RAILWAY ENGINEERING. 

Andrews's Handbook for Street Railway Engineers 3X5 inches^ mor. 1 25 

Berg's Buildings and Structures of American Railroads 4to, 5 00 

Brooks's Handbook of Street Railroad Location 16mo, mor. 1 50 

* Burt's Railway Station Service l2mo, 2 00 

Butts's Civil Engineer's Field-book 16mo, mor. 2 50 

Crandall's Railway and Other Earthwork Tables Svo, 1 50 

Crandall and Barnes's Railroad Surveying 16mo, mor. 2 00 

* Crockett's Methods for Earthwork Computations Svo, 1 50 

Dredge's History of the Pennsylvania Railroad. (1S79) Paper, 5 00 

Fisher's Table of Cubic Yards Cardboard, 25 

* Gilbert Wightman and Saunders's Subways and Tunnels of New York. Svo, 4 00 
Godwin's Railroad Engineers' Field-book and Explorers' Guide. . 16mo, mor. 2 50 



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Hudson's Tables for Calculating the Cubic Contents of Excavations and Pikn- 

bankments 8vo, $1 00 

Ives and Hilts's Problems in Surveying, Railroad Surveying anvl Geodesy 

Ifimo, mor. 

Molitor and Beard's Manual for Resident Engineers 16mo, 

Nagle's Field Manual for Railroad Engineers . .... 16mo, mor. 

* Orrock's Railroad Structures and Estimates 8vo, 

Philbrick's Field Manual for Engineers 16mo, mor. 

Raymond's Railroad Field Geometry 16mo, mor. 

Elements of Railroad Engineering 8vo, 

Railroad Engineer's Field Book. (In Preparation.) 

Roberts' Track Formulae and Tables 16mo. mor. 

Searles's Field Engineering IGmo, mor. 

Railroad Spiral 16mo, mor. 

Taylor's Prismoidal Formulae and Earthwork Svo, 

Webb's Economics of Railroad Construction Large 12mo, 

Railroad Construction 16mo, mor. 

Wellington's Economic Theory of the Location of Railways Large 12mo, 

Wilson's Elements of Railroad-Track and Construction 12mo, 

DRAWING. 

Barr and Wood's Kinematics of Machinery Svo, 

* Bartlett's Mechanical Drawing Svo, 

* " " " Abridged Ed Svo, 

* Bartlett and Johnson's Engineering Descriptive Geometry Svo, 

Blessing and Darling's Descriptive Geometry. (In Press.) 

Elements of Drawing. (In Press.) 

Coolidge's Manual of Drawing Svo, paper, 1 00 

Coolidge and Freeman's Elements of General Drafting for Mechanical Engi- 
neers Oblong 4to. 

Durley's Kinematics of Machines Svo, 

Emch's Introduction to Projective Geometry and its Application Svo, 

Hill's Text-book on Shades and Shadows, and Perspective Svo, 

Jamison's Advanced Mechanical Drawing Svo, 

Elements of Mechanical Drawing .Svo, 

Jones's Machine Design : 

Part I. Kinematics of Machinery Svo, 

Part II. Form, Strength, and Proportions of Parts Svo, 

* Kimball and Barr's Machine Design Svo, 

MacCord's Elements of Descriptive Geometry Svo, 

Kinematics ; or. Practical Mechanism Svo, 

Mechanical Drawing 4to, 

Velocity Diagrams Svo, 

McLeod's Descriptive Geometry. Large 12mo, 

* Mahan's Descriptive Geometry and Stone-cutting Svo, 

Industrial Drawing. (Thompson.) . .Svo, 

Moyer's Descriptive Geometry 8vo, 

Reed's Topographical Drawing and Sketching ' 4to, 

* Reid's Mechanical Drawing. (Elementary and Advanced.) Svo, 

Text-book of Mechanical Drawing and Elementary Machine Design.. Svo, 

Robinson's Principles of Mechanism . ,. = Svo, 

Schwamb and Merrill's Elements of Mechanism Svo, 

Smith (A. W.) and Marx's Machine Design , Svo, 

Smith's (R. S.) Manual of Topographical Drawing. (McMillan.) Svo, 

* Titsworth's Elements of Mechanical Drawing Oblong Svo, 

Tracy and North's Descriptive Geometry. (In Press.) 

Warren's Elements of Descriptive Geometry, Shadows, and Perspective. .Svo, 

Elements of Machine Construction and Drawing Svo, 

Elements of Plane and Solid Free-hand Geometrical Drawing. . . . 12mo, 

General Problems of Shades and Shadows Svo, 

Manual of Elementary Problems in the Linear Perspective of Forms and 

Shadow. ; 12mo, 

Manual of Elementary Projection Drawing 12mo, 

Plane Problems in Elementary Geometry 12mo, 

Weisbach's Kinematics and Power of Transmission. (Hermann and 
Klein.) Svo, 

Wilson's (H. M.) Topographic Surveying Svo, 

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* Wilson's (V. T.) Descriptive Geometry 8vo, $1 50 

Free-hand Lettering 8vo, 1 00 

Free-hand Perspective 8vo, 2 50 

Woolf s Elementary Course in Descriptive Geometry Large 8vo, 3 00 

ELECTRICITY AND PHYSICS. 

* Abegg's Theory of Electrolytic Dissociation, (von Ende.") 12mo, 

Andrews's Hand-book for Street Railway Engineers 3X5 inches mor. 

Anthony and Ball's Lecture-notes on the Theory of Electrical Measure- 
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Anthony and Brackett's Text-book of Physics. . (Magie.). . . .Large 12mo, 

Benjamin's History of Electricity Svo, 

Betts's Lead Refining and Electrolysis Svo, 

* Burgess and Le Chatelier's Measurement of High Temperatures. Third 

Edition Svo, 

Classen's Quantitative Chemical Analysis by Electrolysis. (Boltwood.).Svo, 

* CoUins's Manual of Wireless Telegraphy and Telephony 12mo, 

Crehore and Squier's Polarizing Photo-chronograph Svo, 

* Danneel's Electrochemistry. (Merriam.) l2mo, 

Dawson's "Engineering" and Electric Traction Pocket-book. . . . 16mo, mor. 
Dolezalek's Theory of the Lead Accumulator (Storage Battery), (von Ende.) 

12mo, 

Duhem's Thermodynamics and Chemistry. (Burgess.) Svo, 

Flather's Dynamometers, and the Measurement of Power 12mo, 

* Getman's Introduction to Physical Science 12mo, 

Gilbert's De Magnete. (Mottelay ) Svo, 

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Hering's Ready Reference Tables (Conversion Factors) 16mo, mor. 

* Hobart and Ellis's High-speed Dynamo Electric Machinery Svo, 

Holman's Precision of Measurements Svo, 

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Karapetoff's Experimental Electrical Engineering: 

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Kinzbrunner's Testing of Continuous-current Machines Svo, 

* Koch's Mathematics of Applied Electricity Small Svo, 

Landauer's Spectrum Analysis. (Tingle.) Svo, 

* Lauffer's Electrical Injuries IGmo, 

Lob's Electrochemistry of Organic Compounds. (Lorenz.) Svo, 

* Lyndon's Development and Electrical Distribution of Water Power. .Svo, 

* Lyons's Treatise on Electromagnetic Phenomena. Vols, I. and II. Svo, each, 

* Michie's Elements of Wave Motion Relating to Sound and Light Svo, 

* Morgan's Physical Chemistry for Electrical Engineers 12mo, 

* Norris's Introduction to the Study of Electrical Engineering Svo, 

Norris and Dennison's Course of Problems on the Electrical Characteristics of 

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* Parshall and Hobart's Electric Machine Design 4to, half mor, 12 50^ 

Reagan's Locomotives: Simple. Compound, and Electric. New Edition. 

Large 12mo, 

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* Ryan's Design of Electrical Machinery: 

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Schapper's Laboratory Guide for Students in Physical Chemistry 12mo, 

* Tillman's Elementary Lessons in Heat Svo, 

* Timbie's Elements of Electricity Large 12mo, 

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Tory and Pitcher's Manual of Laboratory Physics Large 12mo, 

Ulke's Modern Electrolytic Copper Refining Svo, 

* Waters's Commercial Dynamo Design Svo, 

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LAW. 

* Brennan's Hand-book of Useful Legal Information for Business Men. 

16mo, mor. $5 00 

* Davis's Elements of Law 8vo, 2 50 

* Treatise on the Military Law of United States 8vo, 7 00 

* Dudley's Military Law and the Procedure of Courts-martial. . Large 12mo, 2 50 

Manual for Courts-martial 16mo, mor. 1 50 

Wait's Engineering and Architectural Jurisprudence 8vo, 6 00 

Sheep, 6 50 

Law of Contracts 8vo, 3 00 

Law of Operations Preliminary to Construction in Engineering and 

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Sheep, 5 50 

MATHEMATICS. 

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Tumeaure and Russell's Public Water-supplies Svo, 

Venable's Garbage Crematories in America Svo, 

Method and Devices for Bacterial Treatment of Sewage Svo, 

Ward and Whipple's Freshwater Biology. (In Press.) 

Whipple's Microscopy of Drinking-water Svo, 

* Typhoid Fever Large 12mo, 

Value of Pure Water Large 12mo, 

Winslow's Systematic Relationship of the Coccaceae Large 12mo, 

MISCELLANEOUS. 

* Burt's Railway Station Service 12mo, 

* Chapin's How to Enamel 12mo, 

Emmons's Geological Guide-book of the Rocky Mountain Excursion of the 

International Congress of Geologists Large Svo, 

Ferrel's Popular Treatise on the Winds Svo, 

Fitzgerald's Boston Machinist , ISmo, 

* Fritz, Autobiography of John Svo, 

Gannett's Statistical Abstract of the World 24mo, 

Haines's American Railway Management 12mo, 

Hanausek's The Microscopy of Technical Products. (Winton) Svo, 

Jacobs's Betterment Briefs. A Collection of Published Papers on Or- 
ganized Industrial Efficiency Svo, 

Metcalfe's Cost of Manufactures, and the Administration of Workshops. .Svo, 

* Parkhurst's Applied Methods of Scientific Management Svo, 

Putnam's Nautical Charts Svo, 

Ricketts's History of Rensselaer Polytechnic Institute 1824-1S94. 

Large 12mo, 

* Rotch and Palm.er's Charts of the Atmosphere for Aeronauts and Aviators. 

Oblong 4to, 

Rotherham's Emphasised New Testament Large Svo, 

Rust's Ex-Meridian Altitude, Azimuth and Star-finding Tables., Svo, 

Standage's Decoration of Wood, Glass, Metal, etc = 12mo, 

Westermaier's Compendium of General Botany. (Schneider) Svo, 

Winslow's Elements of Applied Microscopy 12mO, 

HEBREW AND CHALDEE TEXT-BOOKS. 

Gesenius's Hebrew and Chaldee Lexicon to the Old Testament Scriptures. 

(Tregelles.) Small 4to. half mor, 5 00 

Green's Elementary Hebrew Grammar 12mo, 1 25 



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LIBRARY OF CONGRESS 



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